An experimental study on the catalytic steam reforming of acetic acid was initially performed over a series of co-precipitated Co-Fe unsupported catalysts at relatively low temperatures. It was found that the catalyst activity increased with increasing cobalt content, and the highest performance, with an acetic acid conversion of 100% and an H-2 yield of 96% was obtained over pure cobalt catalyst at 400 degrees C. The catalysts have been systematically characterized by BET, XRD, and HRTEM. The results revealed that the superior activity and stability of pure cobalt catalyst can be ascribed to small particle size, coexistence of metallic cobalt and CoO, and stable H2O adsorption. Furthermore, the mechanism route of acetic acid decomposition on cobalt surface was proposed via DFT calculations. Copyright 0 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.