Abiotic synthesis of formate and short hydrocarbons takes place in serpentinizing vents where some members of vent microbial communities live on abiotic formate as their main carbon source. To better understand the catalytic properties of NiÀ Fe minerals that naturally exist in hydrothermal vents, we have investigated the ability of synthetic NiÀ Fe based nanoparticular solids to catalyze the H 2 -dependent reduction of CO 2 , the first step required for the beginning of prebiotic chemistry. Mono and bimetallic NiÀ Fe nanoparticles with varied Ni-to-Fe ratios transform CO 2 and H 2 into intermediates and products of the acetylcoenzyme A pathway-formate, acetate, and pyruvatein mM range under mild hydrothermal conditions. Furthermore, NiÀ Fe catalysts converted CO 2 to similar products without molecular H 2 by using water as a hydrogen source. Both CO 2 chemisorption analysis and post-reaction characterization of materials indicate that Ni and Fe metals play complementary roles for CO 2 fixation.