Supported gold catalysts highly active for low-temperature CO oxidation were prepared by using AuPPh3NO3 complex as a Au-metal precursor and wet as-precipitated iron hydroxide and titanium hydroxide as support precursors. Effects of catalyst preparation conditions on the performance for low-temperature CO oxidation were studied. Metal-hydroxide precipitation conditions and heating rates of temperature-programmed calcination altered significantly the performance of the supported gold catalysts. To elucidate key factors responsible for the effects the catalysts were characterized by EXAFS, TEM, XRD, and N-2 adsorption. Changes in the activities of both Au/Fe oxide and Au/Ti oxide catalysts originated mainly from changes of the Au particle size distribution. It was also found that states of the mesoporous support precursors upon attaching the An precursor onto them and during the temperature-programmed calcination appeared to be of great importance in obtaining dispersed Au nanoparticles on oxide surfaces.