An apparatus, system, and method generate hydrogen through a controlled chemical reaction between water and a chemical hydride. The invention includes a chemical hydride isolated from water by a water-selective membrane. A fluid containing water is brought into contact with the water-selective membrane. The water diffuses through the water-selective membrane and reacts with the chemical hydride. The water diffuses through the membrane at a predetermined rate based on a water concentration gradient across the water-selective membrane. The water-selective membrane is substantially impermeable to elements and molecules other than water. Hydrogen generated within the chemical hydride is collected and used in various applications.