In this work the performance of CaO-doped Ni/ZrO2 catalysts in ethanol steam reforming was studied. The addition of CaO did not affect the morphology or the crystalline structure of the support. On the contrary, Ni reducibility markedly increased. Moreover, the Lewis acidity of zirconia gradually decreased as the CaO content increased, thus inhibiting coke deposition and improving the carbon balance. The addition of a basic oxide helps to prevent some of the side reactions responsible for coke formation and deposition, that can gradually deactivate the catalyst. (C) 2013 Elsevier B.V. All rights reserved.