MgAl2O4 spinel oxide-supported Ni catalysts modified with Pr have been prepared by wet impregnation method with 8 wt.% Ni and variable loadings of Pr (0-7 wt.%). The samples were characterized by ICP, BET, XRD, TPR, SEM, Raman and TG-TPO and they were tested in ethanol steam reforming reaction. The XRD of the samples revealed the presence of spinel phase MgAl2O4. NiO and weak lines of PrO2/Pr6O11. The addition of Pr slowed down the deactivation rate affecting the amount and the type of carbon deposit. Under reactive conditions, the system with 2.6 Pr wt.% showed the best performance and although it presented filamentous carbon, this catalytic system kept around 80% ethanol conversion during the reaction time (40 h) under severe reforming conditions without reactor plugging. (C) 2011 Elsevier B.V. All rights reserved.