Disclosed is a stabilized chlorine dioxide generating composition containing an oxy-chlorine salt, an acid source, optionally a free halogen source, and an endothermic agent. The endothermic agent neutralizes heat evolved by exothermic reaction of the oxy-chlorine salt by the endothermic reaction of the endothermic agent. Since the endothermic reaction eliminates and/or mitigates propagation of the exothermic reaction of the oxy-chlorine salt from a localized area through the total mass of the material, the chlorine dioxide generating composition is thereby stabilized during making, storing, or shipping the composition.