Co-Ni bimetallic aerogel catalysts with various Co/Ni ratios were synthesized by the sol gel method followed by the supercritical drying process. The catalysts were characterized by XRD, H-2-TPR, HRTEM, BET, TG and FESEM. It showed that the Co/Ni ratio influenced the micro-structure of the Co-Ni bimetallic aerogel catalysts. The formation of homogeneous metal alloy on the bimetallic catalysts was observed after the reduction. In addition, catalysts with higher Co/Ni ratios showed smaller active metal particle sizes. The activities of the aerogel catalysts in terms of CH4 conversion were found to be in the order of 5Co5Ni approximate to 3Co7Ni > 7Co3Ni > 10Ni >> 10Co. 5Co5Ni exhibited the highest CH4 conversion in methane Oxy-CO2 reforming, which is 16% and 55% greater than those of 10Ni and 10Co, respectively. The difference between the catalytic performances could mainly be attributed to the combined effect of the kinetics, the geometric and the SMSI effects. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.