Monometallic copper and nickel catalysts supported on cerium-manganese mixed oxides are prepared, characterized and evaluated for the Water Gas Shift (WGS) reaction. Active metal loading of 2.5 wt% and 7.5 wt% are used to impregnate MnOx-CeO2 supports with 30% and 50% Mn:Ce molar ratio. The structure of the samples strongly depends on both the active metal employed and the manganese content in the mixed support. For both Cu and Ni samples, the best catalytic behavior is found in samples supported on the MnOx-CeO2 oxides with 30% Mn:Ce molar ratio, as a result of the presence of CuxMnyO4 spinel-type phases in the case of copper catalysts and the presence of a NiMnO3 mixed oxide with defect ilmenite structure in the case of nickel catalysts. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.