The performance of hydrogen production from steam reforming of ethanol were investigated by using the K-doped 12CaO center dot 7Al(2) O-3 catalyst (defined as C12A7-O-/x%K). The conversion of ethanol and hydrogen yield over C12A7-O-/x%K catalyst mainly depended on the temperature, K-doping amount, steam-to-carbon ratios (S/C) and contact time (W/F). In order to identify the catalyst's characteristic and active species on the catalyst's surface, Brunauer-Emmett-Teller (BET) surface area, CO2 temperature programmed desorption (CO2TPD), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) were carried out. Based on the characterization, it was found that active oxygen species and doped potassium play important roles in steam reforming of ethanol over C12A7-O-/27.3%K catalyst.