Au supported on gamma-Al2O3 prepared by deposition-precipitation (DP) using urea is found to be a highly active catalyst for the total oxidation of HCHO at room temperature under humid air, without the need for a reducible oxide as support. In-situ DRIFTS studies suggested that the surface hydroxyl groups played a key role in the partial oxidation of HCHO into the formate intermediates, which can be further oxidized into CO2 and H2O with participation of nano-Au. This study challenges the traditional idea of supporting noble metals on reducible oxides for HCHO oxidation at room temperature.