High-throughput near-infrared imaging was used to distinguish catalyst activity for low-temperature methane steam-reforming. Geminal hydroxyls of reduced ceria were depicted during methane reforming at 673 K. The changes in absorbance maps under various water partial pressures showed evidence of formate intermediate formations without redox exchanges. Higher resolution was observed in absorbance change images than that of thermal images obtained from catalyst surface self-emissions. The experimental results illustrated higher activity of pure rhodium catalyst than that of bimetallic ones, likely because of the high dispersion of rhodium on the catalyst support. Moreover, the reaction was accelerated when high surface area silica was added because more reduced sites were exposed. Our filter bandwidths limited our interest in band-shift distribution of geminal hydroxyl band during the reduction process. (c) 2005 American Institute of Chemical Engineers.