diff --git a/diffusivityModel/GasState/GasState.C b/diffusivityModel/GasState/GasState.C
new file mode 100644
index 0000000..684c232
--- /dev/null
+++ b/diffusivityModel/GasState/GasState.C
@@ -0,0 +1,130 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "GasState.H"
+
+#include "diffusivityModel.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+// const dataType Foam::GasState::staticData();
+
+
+// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+inline const Foam::PtrList<Foam::GasState::thermoType> &Foam::GasState::thermos()
+{
+    return diffusivityModel::thermoData();
+}
+
+
+inline const Foam::GasState::thermoType &Foam::GasState::thermos(label i)
+{
+    return thermos()[i];
+}
+
+
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::GasState::GasState(const scalar p, const scalar T, const label n)
+:
+    p_(p),
+    T_(T),
+    Y_(n, 0.0)
+{
+    Y_[0] = 1.0;
+}
+
+
+Foam::GasState::GasState(const scalar p, const scalar T, const scalarField &Y)
+:
+    p_(p),
+    T_(T),
+    Y_(Y)
+{
+    scalar sumY = Foam::sum(Y_);
+
+    Y_ /= sumY;
+}
+
+
+Foam::GasState::GasState(const scalar p, const scalar T, tmp<scalarField> Y)
+:
+    p_(p),
+    T_(T),
+    Y_(Y)
+{
+    scalar sumY = Foam::sum(Y_);
+
+    Y_ /= sumY;
+}
+
+
+Foam::GasState::GasState(const GasState& state)
+:
+    p_(state.p_),
+    T_(state.T_),
+    Y_(state.Y_)
+{}
+
+
+// * * * * * * * * * * * * * * * * Selectors * * * * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+Foam::GasState::~GasState()
+{}
+
+
+// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * * //
+
+void Foam::GasState::operator=(const GasState& rhs)
+{
+    // Check for assignment to self
+    if (this == &rhs)
+    {
+        FatalErrorInFunction
+            << "Attempted assignment to self"
+            << abort(FatalError);
+    }
+}
+
+// * * * * * * * * * * * * * * Friend Functions  * * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * Friend Operators * * * * * * * * * * * * * * //
+
+
+// ************************************************************************* //
diff --git a/diffusivityModel/GasState/GasState.H b/diffusivityModel/GasState/GasState.H
new file mode 100644
index 0000000..f1b7d39
--- /dev/null
+++ b/diffusivityModel/GasState/GasState.H
@@ -0,0 +1,177 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::GasState
+
+Description
+
+SourceFiles
+    GasStateI.H
+    GasState.C
+    GasStateIO.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef GasState_H
+#define GasState_H
+
+#include "thermoPhysicsTypes.H"
+#include "scalarField.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// Forward declaration of classes
+class Istream;
+class Ostream;
+
+// Forward declaration of friend functions and operators
+class GasState;
+Istream& operator>>(Istream&, GasState&);
+Ostream& operator<<(Ostream&, const GasState&);
+
+
+/*---------------------------------------------------------------------------*\
+                         Class GasState Declaration
+\*---------------------------------------------------------------------------*/
+
+class GasState
+{
+public:
+
+    // Data type
+
+        typedef gasHThermoPhysics thermoType;
+
+private:
+    // Private data
+
+        //- Description of data_
+        scalar p_;
+
+        //- Description of data_
+        scalar T_;
+
+        //- Description of data_
+        scalarField Y_;
+
+
+    // Private Member Functions
+
+        //- Disallow default bitwise copy construct
+        GasState(const GasState&);
+
+        //- Disallow default bitwise assignment
+        void operator=(const GasState&);
+
+        //- Static data staticData
+        inline const PtrList<thermoType> &thermos();
+
+        inline const thermoType &thermos(label i);
+
+
+public:
+
+    // Static data members
+
+        //- Static data staticData
+        // static const dataType staticData;
+
+
+    // Constructors
+
+        //- Construct null
+        GasState();
+
+        //- Construct from components
+        GasState(const scalar p, const scalar T, const label n);
+
+        GasState(const scalar p, const scalar T, const scalarField &Y);
+
+        GasState(const scalar p, const scalar T, tmp<scalarField> Y);
+
+        //- Construct from Istream
+        GasState(Istream&);
+
+        //- Construct as copy
+
+
+    //- Destructor
+    ~GasState();
+
+
+    // Member Functions
+
+        // Access
+
+        inline scalar T() const;
+
+        inline scalar &T();
+
+        inline scalar p() const;
+
+        inline scalar &p();
+
+        inline scalar Y(label i) const;
+
+        inline const scalarField &Y() const;
+
+        inline scalarField &Y();
+
+        // Check
+
+        // Edit
+
+        // Write
+
+
+    // Member Operators
+
+
+    // Friend Functions
+
+    // Friend Operators
+
+    // IOstream Operators
+
+        friend Istream& operator>>(Istream&, GasState&);
+        friend Ostream& operator<<(Ostream&, const GasState&);
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "GasStateI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/diffusivityModel/GasState/GasStateI.H b/diffusivityModel/GasState/GasStateI.H
new file mode 100644
index 0000000..7b7a7f7
--- /dev/null
+++ b/diffusivityModel/GasState/GasStateI.H
@@ -0,0 +1,100 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+inline Foam::scalar Foam::GasState::T() const
+{
+    return T_;
+}
+
+
+inline Foam::scalar &Foam::GasState::T()
+{
+    return T_;
+}
+
+
+inline Foam::scalar Foam::GasState::p() const
+{
+    return p_;
+}
+
+
+inline Foam::scalar &Foam::GasState::p()
+{
+    return p_;
+}
+
+
+inline Foam::scalar Foam::GasState::Y(label i) const
+{
+    return Y_[i];
+}
+
+
+inline const Foam::scalarField &Foam::GasState::Y() const
+{
+    return Y_;
+}
+
+
+inline Foam::scalarField &Foam::GasState::Y()
+{
+    return Y_;
+}
+
+
+
+// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * Friend Functions  * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * Friend Operators  * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * Ostream Operator  * * * * * * * * * * * * * //
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+
+// ************************************************************************* //
diff --git a/diffusivityModel/Make/files b/diffusivityModel/Make/files
index 8297da0..2c49ca8 100644
--- a/diffusivityModel/Make/files
+++ b/diffusivityModel/Make/files
@@ -9,6 +9,8 @@ Coulomb/Coulomb.C
 N64/N64.C
 CrossSection/CrossSection.C
 
+GasState/GasState.C
+
 diffusivityModel/diffusivityModel.C
 
 LIB = $(FOAM_USER_LIBBIN)/libdiffusivityModel
diff --git a/diffusivityModel/Make/options b/diffusivityModel/Make/options
index aef5940..6006f0a 100644
--- a/diffusivityModel/Make/options
+++ b/diffusivityModel/Make/options
@@ -8,6 +8,7 @@ EXE_INC = \
     -ICoulomb \
     -IN64 \
     -ICrossSection \
+    -IGasState \
     -IdiffusivityModel \
     -I$(LIB_SRC)/finiteVolume/lnInclude \
     -I$(LIB_SRC)/meshTools/lnInclude \
diff --git a/diffusivityModel/diffusivityModel/diffusivityModel.C b/diffusivityModel/diffusivityModel/diffusivityModel.C
index f5c08f7..16d7594 100644
--- a/diffusivityModel/diffusivityModel/diffusivityModel.C
+++ b/diffusivityModel/diffusivityModel/diffusivityModel.C
@@ -30,7 +30,6 @@ License
 #include "volFieldsFwd.H"
 #include "scalarMatrices.H"
 #include "multiComponentMixture.H"
-#include "thermoPhysicsTypes.H"
 
 #include "Particle.H"
 #include "Electron.H"
@@ -43,11 +42,15 @@ License
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
-// const dataType Foam::diffusivityModel::staticData();
+const Foam::PtrList<Foam::gasHThermoPhysics> *Foam::diffusivityModel::thermoData_ = NULL;
 
 
 // * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
 
+const Foam::PtrList<Foam::gasHThermoPhysics> &Foam::diffusivityModel::thermoData()
+{
+    return *thermoData_;
+}
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
@@ -410,6 +413,11 @@ Foam::diffusivityModel::diffusivityModel(const psiReactionThermo& thermo)
 
     const volScalarField::Mesh &mesh = thermo_.composition().Y(0).mesh();
 
+    if (thermoData_ == NULL)
+    {
+        thermoData_ = &(mcm.speciesData());
+    }
+
     dictionary transports
     (
         IFstream
diff --git a/diffusivityModel/diffusivityModel/diffusivityModel.H b/diffusivityModel/diffusivityModel/diffusivityModel.H
index d310380..e841a3f 100644
--- a/diffusivityModel/diffusivityModel/diffusivityModel.H
+++ b/diffusivityModel/diffusivityModel/diffusivityModel.H
@@ -39,6 +39,7 @@ SourceFiles
 #include "scalar.H"
 #include "autoPtr.H"
 #include "psiReactionThermo.H"
+#include "thermoPhysicsTypes.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -66,6 +67,9 @@ class diffusivityModel
 {
     // Private data
 
+        //- Static data staticData
+        static const PtrList<gasHThermoPhysics> *thermoData_;
+
         //- Reference to thermo object
         const psiReactionThermo& thermo_;
 
@@ -151,6 +155,7 @@ public:
 
         //- Static data staticData
         // static const dataType staticData;
+        static const PtrList<gasHThermoPhysics> &thermoData();
 
 
     // Constructors