In this work the effects of steam-to-carbon ratio (S/C), and addition of H-2 or O-2 to the feed on the product yields and carbon deposition in the steam reforming (SR) of ethanol over Ni/MgAl2O4, Ni/Ce0.6Zr0.4O2, and Ni/CeO2 at 600 degrees C have been investigated. Increasing the S/C-ratio from 1.6 to 8.3 over Ni/MgAl2O4 increased conversion of ethanol as well as the yield of H-2, while the carbon deposition and yield of hydrocarbons decreased. Oxygen addition at S/C-ratio of 6 over Ni/MgAl2O4, Ni/Ce0.6Zr0.4O2, and Ni/CeO2 increased conversion, decreased the yield of hydrocarbons, and led to a decrease in the carbon deposition. Carbon deposition was almost eliminated over Ni/MgAl2O4 and Ni/Ce0.6Zr0.4O2 at an O/C-ratio of roughly 0.8 or higher. The penalty of adding O-2 was a decrease in the yield of H-2 from 70% at O/C = 0 to 50% at O/C = 0.8-1. A 90 h test at O/C = 1.1, S/C = 6, and 600 degrees C over Ni/MgAl2O4 showed stable behavior and an average rate of carbon deposition of less than 7 mu g C/g(Cat) h. The results indicate that stable operation of ethanol SR is only possible under oxidative conditions. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.