In this paper we present a detailed design study of a novel apparatus for safely generating hydrogen (H-2) on demand according to a novel method, using a controlled chemical reaction between water (H2O) and sodium (Na) metal that yields hydrogen gas of sufficient purity for direct use in fuel cells without risk of contaminating sensitive catalysts. The apparatus consists of a first pressure vessel filled with liquid H2O with an overpressure of nitrogen (N-2) gas above the H2O reactant, and a second pressure vessel that stores solid Na reactant. Hydrogen gas is generated above the solid Na when H2O reactant is introduced using a regulator that senses when the downstream pressure of H-2 gas above the solid Na reactant has dropped below a threshold value. The sodium hydroxide (NaOH) byproduct of the hydrogen producing reaction, is collected within the apparatus for later reprocessing by electrolysis, to recover the Na reactant. Copyright (C) 2015, The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications, LLC.