Nickel catalysts supported over ZnAl2O4 modified by Ce or/and Zr addition were studied in the steam reforming of ethanol under more severe reaction conditions such as a lower extent of feed dilution and lower space velocities. The catalysts were stable at 650 C during 35 h in time on stream. The main reaction products were H-2, CO2, CO, C2H4O and small amounts of CH4 and C2H4. The catalyst supported over CeO2-ZnAl2O4 was the most active and showed the highest hydrogen selectivity. The addition of ZrO2 decreased the activity and favored the CO production. The lowest degree of Ni2+ reduction over Ni/ZAZr could explain the worst performance of this system. Otherwise, the highest Ni2+ dispersion and the high oxygen mobility from ceria or from Ni-Ce boundary allowed a higher residual activity and an improved coking resistance. (C) 2010 Elsevier B.V. All rights reserved.