diff --git a/Phreeqc.cpp b/Phreeqc.cpp
index 4236a163..766a0ba2 100644
--- a/Phreeqc.cpp
+++ b/Phreeqc.cpp
@@ -978,9 +978,6 @@ void Phreeqc::init(void)
 	/* ----------------------------------------------------------------------
 	*   ISOTOPES
 	* ---------------------------------------------------------------------- */
-	//count_master_isotope	= 0;
-	//master_isotope			= NULL;
-	//max_master_isotope		= MAX_ELTS;
 	initial_solution_isotopes = FALSE;
 	calculate_value_hash_table = NULL;	
 	count_isotope_ratio		= 0;
@@ -2271,12 +2268,6 @@ Phreeqc::InternalCopy(const Phreeqc *pSrc)
 	/* ----------------------------------------------------------------------
 	*   ISOTOPES
 	* ---------------------------------------------------------------------- */
-	/*
-	count_master_isotope	= 0;
-	master_isotope			= NULL;
-	max_master_isotope		= MAX_ELTS;
-	*/
-
 	for (int i = 0; i < (int)pSrc->master_isotope.size(); i++)
 	{
 		struct master_isotope *master_isotope_ptr = master_isotope_store(pSrc->master_isotope[i]->name, FALSE);
diff --git a/Phreeqc.h b/Phreeqc.h
index a261d851..03698287 100644
--- a/Phreeqc.h
+++ b/Phreeqc.h
@@ -1725,11 +1725,6 @@ protected:
 	/* ----------------------------------------------------------------------
 	*   ISOTOPES
 	* ---------------------------------------------------------------------- */
-	//struct name_coef match_tokens[50];
-	//int count_match_tokens;
-	//int count_master_isotope;
-	//struct master_isotope **master_isotope;
-	//int max_master_isotope;
 	std::vector<master_isotope*> master_isotope;
 	int initial_solution_isotopes;
 	std::vector<struct calculate_value*> calculate_value;
diff --git a/isotopes.cpp b/isotopes.cpp
index d6f30cba..d5585d03 100644
--- a/isotopes.cpp
+++ b/isotopes.cpp
@@ -478,7 +478,6 @@ add_isotopes(cxxSolution &solution_ref)
 	/*
 	 * zero out isotopes
 	 */
-	//for (i = 0; i < count_master_isotope; i++)
 	for (i = 0; i < (int)master_isotope.size(); i++)
 	{
 		master_isotope[i]->moles = 0;
@@ -1351,13 +1350,6 @@ master_isotope_store(const char *name, int replace_if_found)
 	}
 	else
 	{
-		//n = count_master_isotope++;
-		///* make sure there is space in s */
-		//if (count_master_isotope >= max_master_isotope)
-		//{
-		//	space((void **) ((void *) &master_isotope), count_master_isotope,
-		//		  &max_master_isotope, sizeof(struct master_isotope *));
-		//}
 		n = (int)master_isotope.size();
 		master_isotope.resize((size_t)n + 1);
 		/* Make new master_isotope structure */
diff --git a/mainsubs.cpp b/mainsubs.cpp
index 6e49dddd..d069c736 100644
--- a/mainsubs.cpp
+++ b/mainsubs.cpp
@@ -98,9 +98,6 @@ initialize(void)
 
 	space((void **) ((void *) &logk), INIT, &max_logk, sizeof(struct logk *));
 
-	//space((void **) ((void *) &master_isotope), INIT, &max_master_isotope,
-	//	  sizeof(struct master_isotope *));
-
 /*
  *   Create hash tables
  */
diff --git a/structures.cpp b/structures.cpp
index 79d43539..de7c1e50 100644
--- a/structures.cpp
+++ b/structures.cpp
@@ -318,7 +318,6 @@ clean_up(void)
 	count_phases = 0;
 	count_s = 0;
 	count_logk = 0;
-	//count_master_isotope = 0;
 	count_rates = 0;
 	count_inverse = 0;
 	count_save_values = 0;