BACKGROUND: Selective CO oxidation was studied in a hydrogen-rich environment over monolithic Au/MgO/Al2O3 catalysts at 50150 degrees C. The wash-coating of cordierite monoliths with colloidal Al2O3 was followed by wet impregnation of MgO; the subsequent deposition of Au was achieved using various methods. All catalysts were characterized using ICP and ESEM. RESULTS: Homogenous deposition-precipitation was found to be the best Au loading method among those tested for monoliths. The CO conversion over 1%(w/w) Au/1.25%(w/w) MgO/Al2O3 was ca 80% at 90 degrees C. Increasing the Au content of the catalyst from 0.16 to 1.0%(w/w) increased CO conversion and shifted the required temperature to lower values. A similar trend was also observed for maximum CO conversion at increasing W/F-CO ratios. The addition of MgO was beneficial for CO conversion. CONCLUSION: Although CO conversion of ca 80% was lower than that achieved with particulate catalysts, it is high enough as a starting point for further improvement considering the superiority of monolithic supports for practical applications. (C) 2011 Society of Chemical Industry