The use of porous silicon as an energy carrier is investigated. NaOH and solid Mg alloy are used to introduce OH- in water to react with the porous silicon and the porous silicon treated with Mg alloy in water is converted to transparent silicon oxide hydride. The amount and release rate of hydrogen from the reaction between porous silicon and water are determined and the efficiency is also studied. The total amount of released hydrogen does not vary much with the pH value but the release rate is sensitive to the pH value. The average amount of hydrogen produced form porous silicon can reach 63.2 mmol per gram of porous silicon. A moderate rate of about 1.77 mol of H(2) per mol of porous silicon can be obtained per day with the aid of the Mg alloy. This technique is potential useful in supplying hydrogen to fuel cells at normal temperature. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.