A system and a method of storage and dissolution of solid catholyte are provided. The system and the method employ a solid medium having a controlled surface from which solid catholyte particles suspended within a matrix of encapsulating species are dissolved and hydrolyzed producing hydrogen peroxide to be used in semi fuel cells of undersea vehicles. Encapsulating species are also dissolved and hydrolyzed rendering products completely usable in the semi fuel cell. Sodium peroxide is preferably used as the solid catholyte and potassium superoxide and/or sodium hydroxide are preferably used as encapsulating species.