diff --git a/Cantera/src/SpeciesThermo.h b/Cantera/src/SpeciesThermo.h
index 2753da0cb..e4c671170 100755
--- a/Cantera/src/SpeciesThermo.h
+++ b/Cantera/src/SpeciesThermo.h
@@ -80,7 +80,7 @@ namespace Cantera {
             doublereal* s_R) const=0;
 
         /**
-         * Like update, but only updates position k.
+         * Like update, but only updates the species k.
          */
         virtual void update_one(int k, doublereal T, 
             doublereal* cp_R, 
diff --git a/Cantera/src/SpeciesThermoFactory.cpp b/Cantera/src/SpeciesThermoFactory.cpp
index ad7fc8e86..ecba83a63 100755
--- a/Cantera/src/SpeciesThermoFactory.cpp
+++ b/Cantera/src/SpeciesThermoFactory.cpp
@@ -40,6 +40,8 @@ namespace Cantera {
         sparray.getChildren("species",sp);
         int ns = sp.size();
         for (int n = 0; n < ns; n++) {
+	  XML_Node* spNode = sp[n];
+	  if (spNode->hasChild("thermo")) {
             const XML_Node& th = sp[n]->child("thermo");
             if (th.hasChild("NASA")) has_nasa = 1;
             if (th.hasChild("Shomate")) has_shomate = 1;
@@ -49,6 +51,10 @@ namespace Cantera {
                 else throw CanteraError("newSpeciesThermo",
                     "poly with order > 1 not yet supported");
             }
+	  } else {
+	    throw UnknownSpeciesThermoModel("getSpeciesThermoTypes:",
+					    spNode->attrib("name"), "missing");
+	  }
         }
     }
 
@@ -75,6 +81,21 @@ namespace Cantera {
     }
 
 
+    SpeciesThermo* SpeciesThermoFactory::newSpeciesThermoOpt(vector<XML_Node*> nodes) {
+        int n = nodes.size();
+        int inasa = 0, ishomate = 0, isimple = 0;
+        for (int j = 0; j < n; j++) {
+	  try {
+            getSpeciesThermoTypes(nodes[j], inasa, ishomate, isimple);
+	  } catch (UnknownSpeciesThermoModel) {
+
+	  }
+        }
+        return newSpeciesThermo(NASA*inasa
+            + SHOMATE*ishomate + SIMPLE*isimple);
+    }
+
+
     SpeciesThermo* SpeciesThermoFactory::newSpeciesThermo(int type) {
         
         switch (type) {
diff --git a/Cantera/src/SpeciesThermoFactory.h b/Cantera/src/SpeciesThermoFactory.h
index 5eec44735..6e52e1b68 100755
--- a/Cantera/src/SpeciesThermoFactory.h
+++ b/Cantera/src/SpeciesThermoFactory.h
@@ -15,12 +15,27 @@
 #define SPECIESTHERMO_FACTORY_H
 
 #include "SpeciesThermo.h"
-//#include "xml.h"
+#include "ctexceptions.h"
 
 namespace Cantera {
 
     class XML_Node;
 
+    /**
+     * Throw a named error for an unknown or missing species thermo
+     * model. 
+     */
+    class UnknownSpeciesThermoModel: public CanteraError {
+    public:
+	UnknownSpeciesThermoModel(string proc, string spName,
+				  string speciesThermoModel) :
+	    CanteraError(proc, "species :" + spName + 
+			 ": Specified speciesThermoPhase model "   
+			 + speciesThermoModel + 
+			 " does not match any known type.") {}
+	virtual ~UnknownSpeciesThermoModel() {}
+    };
+
     /**
      * Factory to build instances of classes that manage the
      * standard-state thermodynamic properties of a set of species.
@@ -33,10 +48,20 @@ namespace Cantera {
             if (!__factory) __factory = new SpeciesThermoFactory;
             return __factory;
         }
-
+	static void deleteFactory() {
+	    if (__factory) {
+	      delete __factory;
+	      __factory = 0;
+	    }
+	}
+	
+	/**
+         * Destructor doesn't do anything. We do not delete statically
+	 * created single instance of this class here, because it would
+	 * create an infinite loop if destructor is called for that
+	 * single instance.
+         */
         virtual ~SpeciesThermoFactory() {
-            delete __factory;
-            __factory = 0;
         }
 
         /**
@@ -46,6 +71,7 @@ namespace Cantera {
         virtual SpeciesThermo* newSpeciesThermo(int type);
         virtual SpeciesThermo* newSpeciesThermo(XML_Node* node);
         virtual SpeciesThermo* newSpeciesThermo(vector<XML_Node*> nodes);
+        virtual SpeciesThermo* newSpeciesThermoOpt(vector<XML_Node*> nodes);
 
     private:
         static SpeciesThermoFactory* __factory;
@@ -78,11 +104,16 @@ namespace Cantera {
     }
 
     inline SpeciesThermo* newSpeciesThermoMgr(vector<XML_Node*> nodes, 
-        SpeciesThermoFactory* f=0) {
+        SpeciesThermoFactory* f=0, bool opt=false) {
         if (f == 0) {
             f = SpeciesThermoFactory::factory();
         }
-        SpeciesThermo* sptherm = f->newSpeciesThermo(nodes);
+	SpeciesThermo* sptherm;
+	if (opt) {
+	  sptherm = f->newSpeciesThermoOpt(nodes);
+	} else { 
+	  sptherm = f->newSpeciesThermo(nodes);
+	}
         return sptherm;
     }