diff --git a/Phreeqc.cpp b/Phreeqc.cpp
index 47122dcf..bece82d1 100644
--- a/Phreeqc.cpp
+++ b/Phreeqc.cpp
@@ -763,7 +763,6 @@ void Phreeqc::init(void)
 	*   Reaction work space
 	*---------------------------------------------------------------------- */
 	// struct trxn;	
-	trxn.token				= 0;
 	for (int i = 0; i < MAX_LOG_K_INDICES; i++)
 	{
 		trxn.logk[i] = 0;
@@ -773,7 +772,6 @@ void Phreeqc::init(void)
 		trxn.dz[i] = 0;
 	}
 	count_trxn              = 0;
-	max_trxn                = MAX_TRXN;
 
 	mb_unknowns             = NULL;
 	count_mb_unknowns       = 0;
@@ -1896,7 +1894,6 @@ Phreeqc::InternalCopy(const Phreeqc *pSrc)
 		trxn.dz[i] = 0;
 	}
 	count_trxn              = 0;
-	max_trxn                = MAX_TRXN;
 	*/
 	/*
 	mb_unknowns             = NULL;
diff --git a/Phreeqc.h b/Phreeqc.h
index 4dcc12d6..0f9555d0 100644
--- a/Phreeqc.h
+++ b/Phreeqc.h
@@ -1530,8 +1530,7 @@ protected:
 	*---------------------------------------------------------------------- */
 	struct reaction_temp trxn;	/* structure array of working space while reading equations
 								species names are in "temp_strings" */
-	int count_trxn;		/* number of reactants in trxn = position of next */
-	int max_trxn;
+	int count_trxn;		        /* number of reactants in trxn = position of next */
 
 	struct unknown_list *mb_unknowns;
 	int count_mb_unknowns;
diff --git a/global_structures.h b/global_structures.h
index d0604682..b6e833bb 100644
--- a/global_structures.h
+++ b/global_structures.h
@@ -813,7 +813,7 @@ struct reaction_temp
 {
 	LDBLE logk[MAX_LOG_K_INDICES];
 	LDBLE dz[3];
-	struct rxn_token_temp *token;
+	std::vector<struct rxn_token_temp> token;
 };
 struct rxn_token_temp
 {								/* data for equations, aq. species or minerals */
diff --git a/mainsubs.cpp b/mainsubs.cpp
index 10654610..d5bbe610 100644
--- a/mainsubs.cpp
+++ b/mainsubs.cpp
@@ -78,10 +78,6 @@ initialize(void)
 	stag_data->exch_f = 0;
 	stag_data->th_m = 0;
 	stag_data->th_im = 0;
-
-	space((void **) ((void *) &trxn.token), INIT, &max_trxn,
-		  sizeof(struct rxn_token_temp));
-
 /*
  *   Create hash tables
  */
diff --git a/parse.cpp b/parse.cpp
index 8931f432..11cc4e26 100644
--- a/parse.cpp
+++ b/parse.cpp
@@ -1025,11 +1025,8 @@ get_species(char **ptr)
 	char string[MAX_LENGTH];
 	int l;
 
-	if (count_trxn + 1 >= max_trxn)
-	{
-		space((void **) ((void *) &(trxn.token)), count_trxn + 1, &max_trxn,
-			  sizeof(struct rxn_token_temp));
-	}
+	if ((size_t) count_trxn + 1 > trxn.token.size()) 
+		trxn.token.resize((size_t)count_trxn + 1);
 	/* coefficient */
 	if (get_coef(&(trxn.token[count_trxn].coef), ptr) == ERROR)
 	{
diff --git a/prep.cpp b/prep.cpp
index b837e060..6bb87951 100644
--- a/prep.cpp
+++ b/prep.cpp
@@ -2861,11 +2861,8 @@ add_potential_factor(void)
 /*
  *   Make sure there is space
  */
-	if (count_trxn + 1 >= max_trxn)
-	{
-		space((void **) ((void *) &(trxn.token)), count_trxn + 1, &max_trxn,
-			  sizeof(struct rxn_token_temp));
-	}
+	if ((size_t)count_trxn + 1 > trxn.token.size())
+		trxn.token.resize((size_t)count_trxn + 1);
 /*
  *   Include psi in mass action equation
  */
@@ -2958,11 +2955,8 @@ add_cd_music_factors(int n)
 	/*
 	 *   Make sure there is space
 	 */
-	if (count_trxn + 3 >= max_trxn)
-	{
-		space((void **) ((void *) &(trxn.token)), count_trxn + 3, &max_trxn,
-			  sizeof(struct rxn_token_temp));
-	}
+	if ((size_t)count_trxn + 3 > trxn.token.size())
+		trxn.token.resize((size_t)count_trxn + 3);
 	/*
 	 *   Include psi in mass action equation
 	 */
diff --git a/structures.cpp b/structures.cpp
index fb94a438..44f96472 100644
--- a/structures.cpp
+++ b/structures.cpp
@@ -291,10 +291,8 @@ clean_up(void)
 	change_surf = (struct Change_Surf *) free_check_null(change_surf);
 
 /* miscellaneous work space */
-
-	//elt_list = (struct elt_list *) free_check_null(elt_list);
 	elt_list.clear();
-	trxn.token = (struct rxn_token_temp *) free_check_null(trxn.token);
+	trxn.token.clear();
 	mb_unknowns = (struct unknown_list *) free_check_null(mb_unknowns);
 	line = (char *) free_check_null(line);
 	line_save = (char *) free_check_null(line_save);
@@ -2620,11 +2618,8 @@ trxn_add(cxxChemRxn &r_ptr, LDBLE coef, int combine)
  */
 	for (size_t j = 0; j < r_ptr.Get_tokens().size(); j++)
 	{
-		if (count_trxn + 1 >= max_trxn)
-		{
-			space((void **) ((void *) &(trxn.token)), count_trxn + 1,
-				  &max_trxn, sizeof(struct rxn_token_temp));
-		}
+		if ((size_t)count_trxn + 1 > trxn.token.size())
+			trxn.token.resize((size_t)count_trxn + 1);
 		trxn.token[count_trxn].name = r_ptr.Get_tokens()[j].name;
 		trxn.token[count_trxn].s = r_ptr.Get_tokens()[j].s;
 		trxn.token[count_trxn].coef = coef * r_ptr.Get_tokens()[j].coef;
@@ -2685,11 +2680,8 @@ trxn_add(struct reaction *r_ptr, LDBLE coef, int combine)
 	next_token = r_ptr->token;
 	while (next_token->s != NULL)
 	{
-		if (count_trxn + 1 >= max_trxn)
-		{
-			space((void **) ((void *) &(trxn.token)), count_trxn + 1,
-				  &max_trxn, sizeof(struct rxn_token_temp));
-		}
+		if ((size_t)count_trxn + 1 > trxn.token.size())
+			trxn.token.resize((size_t)count_trxn + 1);
 		trxn.token[count_trxn].name = next_token->s->name;
 		trxn.token[count_trxn].s = next_token->s;
 		trxn.token[count_trxn].coef = coef * next_token->coef;
@@ -2743,11 +2735,8 @@ trxn_add_phase(struct reaction *r_ptr, LDBLE coef, int combine)
 	next_token = r_ptr->token;
 	while (next_token->s != NULL || next_token->name != NULL)
 	{
-		if (count_trxn + 1 >= max_trxn)
-		{
-			space((void **) ((void *) &(trxn.token)), count_trxn + 1,
-				  &max_trxn, sizeof(struct rxn_token_temp));
-		}
+		if ((size_t)count_trxn + 1 > trxn.token.size())
+			trxn.token.resize((size_t)count_trxn + 1);
 		if (next_token->s != NULL)
 		{
 			trxn.token[count_trxn].name = next_token->s->name;
diff --git a/tidy.cpp b/tidy.cpp
index 0ba1ec98..ce623bfa 100644
--- a/tidy.cpp
+++ b/tidy.cpp
@@ -2873,11 +2873,8 @@ species_rxn_to_trxn(struct species *s_ptr)
 		trxn.token[i].unknown = NULL;
 		trxn.token[i].coef = s_ptr->rxn->token[i].coef;
 		count_trxn = i + 1;
-		if (count_trxn + 1 >= max_trxn)
-		{
-			space((void **) ((void *) &(trxn.token)), count_trxn + 1,
-				  &max_trxn, sizeof(struct rxn_token_temp));
-		}
+		if ((size_t)count_trxn + 1 > trxn.token.size())
+			trxn.token.resize((size_t)count_trxn + 1);
 	}
 	return (OK);
 }
@@ -2916,11 +2913,8 @@ phase_rxn_to_trxn(struct phase *phase_ptr, struct reaction *rxn_ptr)
 		trxn.token[i].unknown = NULL;
 		trxn.token[i].coef = rxn_ptr->token[i].coef;
 		count_trxn = i + 1;
-		if (count_trxn + 1 >= max_trxn)
-		{
-			space((void **) ((void *) &(trxn.token)), count_trxn + 1,
-				  &max_trxn, sizeof(struct rxn_token_temp));
-		}
+		if ((size_t)count_trxn + 1 > trxn.token.size())
+			trxn.token.resize((size_t)count_trxn + 1);
 	}
 	return (OK);
 }