A process for forming uniform distributions of at least one substance in a solid. The process comprises forming a predistribution of the at least one substance in at least one compound, e.g., mixing the at least one substance so that it is distributed throughout the at least one compound, and reacting the at least one compound with water to form a hydroxide, which hydroxide has a larger surface area than the at least one compound. Predistribution must take place before a substantial portion of the compound reacts to form the hydroxide. This process can be used to form a dry powder having at least one substance uniformly distributed therein.