Described are compositions containing a mixture of (a) particulate calcium hypochlorite and (b) an amount of aluminum hydroxide that is sufficient to increase the UN-burn time of the composition by a factor of at least 2.5 compared to that of the calcium hypochlorite, the composition having an available chlorine content of at least 35 weight percent. Further described are solid compositions of (a) granular calcium hypochlorite having a UN Packing Group oxidizer classification of II, and (b) an amount of aluminum hydroxide such that the composition is classified as a Packing Group III Division 5.1 oxidizer or as a non-Division 5.1 oxidizer, the composition having an available chlorine content of at least 40 weight percent. Further described are formed articles prepared from the above-described compositions.