In this article we attempted to review the key issues relevant to tremendous oxidation activity of supported Au catalysts. We described in detail newly developed Au catalysts, remarkably active for low-temperature CO oxidation, using Au phosphine complexes and clusters as precursors for gold metal particles and as-precipitated wet metal hydroxides as precursors for oxide supports. Particular attention was placed on chemical interaction of the Au complexes and clusters with the oxide surfaces and its critical role in preparation of tremendously active supported Au. Simultaneous transformations of both the gold and support precursors during temperature-programmed calcination provoked the formation of Au catalysts highly active for the low-temperature CO oxidation. A new aspect of CO oxidation mechanisms was also discussed.