combined steam and carbon dioxide reforming of methane. Coke deposition, the content of methane and carbon dioxide in syn-gas as well as H(2)/CO ratio were investigated as a function of CO(2)/CH(4) and H(2)O/CH(4) mole ratios at different temperatures and pressures. The ranges of the molar ratios CH(4)/CO(2)/H(2)O in the feed with H(2)/CO = 2.1-2.2 were identified at which reforming of methane is not complicated by coke deposition. For each range optimized CH(4)/CO(2)/H(2)O molar ratios characterized by the lowest content of methane and carbon dioxide in syn-gas were found. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.