diff --git a/SConstruct b/SConstruct
index 7ab499393..c1d678e90 100644
--- a/SConstruct
+++ b/SConstruct
@@ -324,10 +324,6 @@ opts.AddVariables(
         'sphinx_docs',
         """Build HTML documentation for the Python module using Sphinx""",
         False),
-    BoolVariable(
-        'with_adsorbate',
-        """Include thermodynamic model for adsorbates in the Cantera kernel""",
-        True),
     BoolVariable(
         'with_h298modify_capability',
         """Enable changing the 298K heats of formation directly via
diff --git a/doc/sphinx/scons-options.txt b/doc/sphinx/scons-options.txt
index 05b9d822a..8e2054669 100644
--- a/doc/sphinx/scons-options.txt
+++ b/doc/sphinx/scons-options.txt
@@ -137,10 +137,6 @@ of this file is:
     kernel.
     - default: 'yes'
 
-* with_adsorbate: [ yes | no ]
-    Include thermodynamic model for adsorbates in the Cantera kernel
-    - default: 'yes'
-
 * with_h298modify_capability: [ yes | no ]
     Enable changing the 298K heats of formation directly via the C++
     layer.
diff --git a/include/cantera/thermo/AdsorbateThermo.h b/include/cantera/thermo/AdsorbateThermo.h
index 98b706400..7c02dcf8f 100644
--- a/include/cantera/thermo/AdsorbateThermo.h
+++ b/include/cantera/thermo/AdsorbateThermo.h
@@ -120,7 +120,7 @@ public:
     }
 
     //! Returns an integer representing the species index
-    virtual int speciesIndex() const {
+    virtual size_t speciesIndex() const {
         return m_index;
     }
 
@@ -165,7 +165,7 @@ public:
      * @param coeffs    Vector of coefficients used to set the
      *                  parameters for the standard state.
      */
-    void reportParameters(int& n, int& type,
+    void reportParameters(size_t& n, int& type,
                           doublereal& tlow, doublereal& thigh,
                           doublereal& pref,
                           doublereal* const coeffs) const {
@@ -176,7 +176,7 @@ public:
         pref = m_Pref;
         coeffs[0] = m_nFreqs;
         coeffs[1] = m_be;
-        for (int i = 2; i < m_nFreqs+2; i++) {
+        for (size_t i = 2; i < m_nFreqs+2; i++) {
             coeffs[i] = m_freq[i-2];
         }
     }
diff --git a/src/thermo/GeneralSpeciesThermo.cpp b/src/thermo/GeneralSpeciesThermo.cpp
index 634d9cab3..2964c00cc 100644
--- a/src/thermo/GeneralSpeciesThermo.cpp
+++ b/src/thermo/GeneralSpeciesThermo.cpp
@@ -12,10 +12,7 @@
 #include "ShomatePoly.h"
 #include "ConstCpPoly.h"
 #include "cantera/thermo/Mu0Poly.h"
-#ifdef WITH_ADSORBATE
 #include "cantera/thermo/AdsorbateThermo.h"
-#endif
-
 #include "cantera/thermo/SpeciesThermoFactory.h"
 #include <iostream>
 
@@ -157,12 +154,10 @@ void GeneralSpeciesThermo::install(std::string name,
         m_sp[index] = new NasaPoly2(index, minTemp, maxTemp,
                                     refPressure, c);
         break;
-#ifdef WITH_ADSORBATE
     case ADSORBATE:
         m_sp[index] = new Adsorbate(index, minTemp, maxTemp,
                                     refPressure, c);
         break;
-#endif
     default:
         throw UnknownSpeciesThermoModel(
             "GeneralSpeciesThermo::install",
diff --git a/src/thermo/SpeciesThermoFactory.cpp b/src/thermo/SpeciesThermoFactory.cpp
index a90b277d6..ddf5d31b8 100644
--- a/src/thermo/SpeciesThermoFactory.cpp
+++ b/src/thermo/SpeciesThermoFactory.cpp
@@ -18,10 +18,7 @@ using namespace std;
 #include "Nasa9PolyMultiTempRegion.h"
 #include "cantera/thermo/Nasa9Poly1.h"
 
-#ifdef WITH_ADSORBATE
 #include "cantera/thermo/AdsorbateThermo.h"
-#endif
-
 #include "cantera/thermo/SpeciesThermoMgr.h"
 #include "cantera/thermo/speciesThermoTypes.h"
 #include "cantera/thermo/VPSSMgr.h"
@@ -677,7 +674,6 @@ static void installNasa9ThermoFromXML(std::string speciesName,
 }
 
 
-#ifdef WITH_ADSORBATE
 //! Install a Adsorbate polynomial thermodynamic property parameterization for species k into a SpeciesThermo instance.
 /*!
  * This is called by method installThermoForSpecies if a Adsorbate block is found in the XML input.
@@ -719,7 +715,6 @@ static void installAdsorbateThermoFromXML(std::string speciesName,
     copy(freqs.begin(), freqs.end(), coeffs.begin() + 2);
     (&sp)->install(speciesName, k, ADSORBATE, &coeffs[0], tmin, tmax, pref);
 }
-#endif
 
 //================================================================================================
 // Install a species thermodynamic property parameterization
@@ -782,11 +777,9 @@ void SpeciesThermoFactory::installThermoForSpecies
             } else if (f->name() == "NASA9") {
                 installNasa9ThermoFromXML(speciesNode["name"], spthermo, k, tp);
             }
-#ifdef WITH_ADSORBATE
             else if (f->name() == "adsorbate") {
                 installAdsorbateThermoFromXML(speciesNode["name"], spthermo, k, *f);
             }
-#endif
             else {
                 throw UnknownSpeciesThermoModel("installThermoForSpecies",
                                                 speciesNode["name"], f->name());