The catalytic performance for the preferential oxidation of CO over a 1% (w/w) PtAu/CeO2-ZnO catalyst prepared by co-precipitation was investigated using a full 2(k) factorial design with three central points and a 95% confidence interval, in order to screen for the importance of the operating temperature (degrees C) and the H2O and CO2 contents (%) in the simulated reformate gas on the CO conversion and selectivity. The catalyst was characterized by TEM, BET, XRD and FTIR. The temperature and CO2 content had a significant influence on the conversion, whilst the selectivity depended on the temperature only. A face-centered central composite design was then used to evaluate the optimal conditions by simultaneously considering the maximal conversion, selectivity and constraints of the composition of realistic reformate gas. The difference in the estimated response and the experimental one was within +/- 2% and +/- 3% for routing simulated and realistic reformate gases, respectively. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.