diff --git a/Cantera/src/thermo/HKFT_PDSS.cpp b/Cantera/src/thermo/HKFT_PDSS.cpp
index 6e4f79482..e1c3f4a52 100644
--- a/Cantera/src/thermo/HKFT_PDSS.cpp
+++ b/Cantera/src/thermo/HKFT_PDSS.cpp
@@ -6,6 +6,7 @@
 #include "ctml.h"
 #include "HKFT_PDSS.h"
 #include "WaterPDSS.h"
+#include "WaterProps.h"
 
 #include "ThermoPhase.h"
 
@@ -145,6 +146,21 @@ namespace Cantera {
   }
 
   void HKFT_PDSS::initThermo() {
+    
+    /*
+     *  Section to initialize  m_Z_pr_tr and   m_Y_pr_tr
+     */
+    double temp = 273.15 + 25.;
+    double pres = OneAtm;
+    double relepsilon = m_wprops->relEpsilon(temp, pres, 0);
+ 
+    m_Z_pr_tr = -1.0 / relepsilon;
+    //double m_Z_pr_tr = -0.0127803;
+    //printf("m_Z_pr_tr = %20.10g\n",  m_Z_pr_tr ); 
+    double drelepsilondT = m_wprops->relEpsilon(temp, pres, 1);
+    //double m_Y_pr_tr = -5.799E-5;
+    m_Y_pr_tr = drelepsilondT / (relepsilon * relepsilon);
+    //printf("m_Y_pr_tr = %20.10g\n",  m_Y_pr_tr ); 
   }
 
   void HKFT_PDSS::
@@ -345,7 +361,60 @@ namespace Cantera {
     throw CanteraError("HKFT_PDSS::satPressure()", "unimplemented");
     return (0.0);
   }
+
+
+  double HKFT_PDSS::deltaG() {
+    
+    double pbar = m_pres * 1.0E-5;
+    double m_presR_bar = OneAtm * 1.0E-5;
+
+    double sterm = -  m_Entrop_tr_pr * (m_temp - 298.15);
+
+    double c1term = -m_c1*(m_temp * log(m_temp/298.15) - (m_temp - 298.15));
+    double a1term = m_a1 * (pbar - m_presR_bar);
+
+    double a2term = m_a2 * log((2600. + pbar)/(2600. + m_presR_bar));
+
+    double c2term = -m_c2 * (( 1.0/(m_temp - 228.) - 1.0/(298.15 - 228.) ) * (228 - m_temp)/228.
+			     - m_temp / (228.*228.) * log( (298.15*(m_temp-228.)) / (m_temp*(298.15-228.)) ));
+    
+    double a3term = m_a3 / (m_temp - 228.) * (pbar - m_presR_bar);
+
+    double a4term = m_a4 / (m_temp - 228.) * log((2600. + pbar)/(2600. + m_presR_bar));
+
+    double nu = 166027;
+    double r_e_j_pr_tr = m_charge_j * m_charge_j / (m_omega_pr_tr/nu + m_charge_j/3.082);
+  
+    double gval = gstar(m_temp, m_pres, 0);
+
+    double r_e_j = r_e_j_pr_tr + fabs(m_charge_j) * gval;
+
+    double omega_j = nu * (m_charge_j * m_charge_j / r_e_j - m_charge_j / (3.082 + gval)  );
+
+    double relepsilon = m_wprops->relEpsilon(m_temp, m_pres, 0);
+
+    //double Y_pr_tr = -5.799E-5;
+    //double Z_pr_tr = -0.0127803;
+
+    double Z = -1.0 / relepsilon;
+
+    double wterm = - omega_j * (Z + 1.0);
+
+    double wrterm = m_omega_pr_tr * (m_Z_pr_tr + 1.0);
+
+    double yterm = m_omega_pr_tr * m_Y_pr_tr * (m_temp - 298.15);
+
+    double deltaG_calgmol = m_deltaG_tr_pr + sterm + c1term + a1term + a2term + c2term + a3term + a4term + wterm + wrterm + yterm;
+
+    // Convert to Joules / kg
+    double deltaG = deltaG_calgmol * 1.0E3 * 4.184;
+    return deltaG;
+  }
    
+  double HKFT_PDSS::electrostatic_radii_calc() {
+    return 0.0;
+  }
+
   //! Internal formula for the calculation of a_g()
   /*
    * The output of this is in units of Angstroms
diff --git a/Cantera/src/thermo/HKFT_PDSS.h b/Cantera/src/thermo/HKFT_PDSS.h
index 4a30d73db..0b304aeda 100644
--- a/Cantera/src/thermo/HKFT_PDSS.h
+++ b/Cantera/src/thermo/HKFT_PDSS.h
@@ -139,6 +139,9 @@ namespace Cantera {
     virtual void initThermo();
     virtual void setParametersFromXML(const XML_Node& eosdata);
 
+    double deltaG();
+    double electrostatic_radii_calc();
+
   private:
     double ag(const double temp, const int ifunc = 0) const;
     double bg(const double temp, const int ifunc = 0) const;
@@ -155,6 +158,9 @@ namespace Cantera {
      */
     WaterPDSS *m_waterSS;
 
+    //! Current value of the pressure for this object
+    doublereal m_pres;
+
     //! density of standard-state water
     /*!
      * internal temporary variable
@@ -167,6 +173,60 @@ namespace Cantera {
     WaterProps *m_waterProps;
 
 
+    //! Born coefficient for the current ion or species
+
+    doublereal m_born_coeff_j;
+
+    //! Electrostatic radii
+    doublereal r_e_j;
+
+
+    //! Value of deltaG at Tr and Pr    (cal gmol-1)
+    /*!
+     *  Tr = 298.15   Pr = 1 atm
+     */
+    doublereal m_deltaG_tr_pr;
+
+    //! Value of S_j at Tr and Pr    (cal gmol-1 K-1)
+    /*!
+     *  Tr = 298.15   Pr = 1 atm
+     */
+    doublereal m_Entrop_tr_pr;
+
+    //! a1 coefficient (cal gmol-1 bar-1)
+    doublereal m_a1;
+
+    //! a2 coefficient (cal gmol-1)
+    doublereal m_a2;
+
+    //! c1 coefficient (cal gmol-1 K-1)
+    doublereal m_c1;
+    
+    //! c2 coefficient (cal K gmol-1)
+    doublereal m_c2;
+
+    //! a3 coefficient (cal K gmol-1 bar-1)
+    doublereal m_a3;
+
+    //! a4 coefficient (cal K gmol-1)
+    doublereal m_a4;
+
+    //! omega_pr_tr coefficient(cal gmol-1)
+    doublereal m_omega_pr_tr;
+
+    //! y = dZdT = 1/(esp*esp) desp/dT
+    double m_Y_pr_tr;
+    //double m_Y_pr_tr = -5.799E-5;
+    double m_Z_pr_tr;
+    //double m_Z_pr_tr = -0.0127803;
+    //! Reference pressure is 1 atm in units of bar= 1.0132
+    doublereal m_presR_bar;
+
+
+    //! Charge of the ion
+    doublereal m_charge_j;
+
+    WaterProps *m_wprops;
 
   };
 
diff --git a/Cantera/src/thermo/WaterProps.h b/Cantera/src/thermo/WaterProps.h
index 7bf9601a1..f486ba8d6 100644
--- a/Cantera/src/thermo/WaterProps.h
+++ b/Cantera/src/thermo/WaterProps.h
@@ -135,7 +135,7 @@ namespace Cantera {
      *   value at 25C and 1 atm, relEps = 78.38
      * 
      */
-    static double relEpsilon(double T, double P_pascal,  int ifunc = 0);
+    double relEpsilon(double T, double P_pascal,  int ifunc = 0);
 
     
     //! ADebye calculates the value of A_Debye as a function