Hydrogen production by supercritical water gasification (SCWG) of valine as a model for protein was examined in a fixed-bed reactor at 28 MPa. The effect of reaction temperature (500-710 degrees C), type of catalyst (AC, Ni-Y/AC, Ni-Pt/AC, and Ni-Pd/AC), and LHSV (24 -72 h(-1)) on the extent of gasification and gas composition was investigated. Total gas yield increased with increasing temperature up to 710 degrees C while carbon gasification efficiency (CGE) reached the highest value of 98.1% at 600 degrees C over the Ni-Y/AC catalyst. The three Ni-based catalysts promoted hydrogen formation reactions greater than the AC. In particular the Ni-Pt/AC and Ni Pd/AC catalysts effectively reformed C2+ hydrocarbons intermediates to H-2 and CO2. The Ni-Y/AC catalyst at 650 degrees C completely destroyed nitrogen-containing organic intermediates such as amines in the liquid effluent. The presence of Pt and Pd significantly suppressed the crystallization of Ni metal supported on AC in supercritical water. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.