This paper investigated the glow discharge plasma electrolysis (GDPE) of methanol solutions for hydrogen generation. it is known that H(2) and HCHO are the dominant products of methanol decomposition during GDPE. The experimental results indicate that high-energy electrons are the most important species to initiate methanol decomposition. Likewise, it was shown that discharged polarity, discharged voltage, and methanol concentration have important influences on hydrogen yield, energy consumption, hydrogen concentration, and hydrogen and formaldehyde output. The hydrogen yield (G(H(2))) of cathodic GDPE (GGDPE) was found to be higher than that of anodic GDPE (AGDPE). In addition, the hydrogen concentration in liberated gas from CGDPE remains above 88% after the separation of HCHO when the applied voltage is higher than 750 V. The energy consumption (W(r)) of CGDPE is significantly less than AGDPE. Furthermore, W(r) decreased with the increase in discharged voltage, while G(H(2)) increased with methanol concentration. The experimental results show that the GDPE of methanol solutions is a promising technique for the simultaneous production of hydrogen and formaldehyde. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.