In this paper, high efficient production of CO-free hydrogen from formaldehyde (HCHO) aqueous solution catalyzed by various nano-metal catalysts was reported. it was found that nano-metal catalyst could catalyze formaldehyde into hydrogen and formic acid under room temperature and atmospheric pressure. Among Pt, Au, Ni, and Cu nano-metal particles, nano-Cu catalyst exhibited the highest activity and the long-term stability. The temperature seems influence the reaction significantly. For example, when the temperature was increased from 0 to 60 degrees C, the rate of hydrogen production increases from 2.34 to 140 mL min(-1) g(-1) catalyst over nano-Cu catalyst. Hydrogen was produced via the formic acid intermediate. When NaOH concentration was high, Cannizzaro reaction occurred, which resulted in the retardation of hydrogen generation at high concentration of NaOH and HCHO. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.