An apparatus, system, and method are disclosed for generating a gas. One or more liquid permeable pouches each define a cavity that contains a solid anhydrous reactant, such as a chemical hydride. A reaction chamber made of a heat, chemical and/or pressure resistant material receives the one or more pouches from a pouch feeder that transfers the one or more pouches into the reaction chamber successively at a feed rate. One or more liquid sources inject a liquid reactant into the reaction chamber so that the liquid reactant contacts a portion of the one or more pouches. The one or more liquid sources inject the liquid reactant at an injection rate that corresponds to the feed rate. A gas outlet releases a gas, such as hydrogen, oxygen, ammonia, borazine, nitrogen, or a hydrocarbon, that is produced by a reaction between the solid reactant and the liquid reactant.