Metal complexes of Au, Pd, and Ag are transformed into metal particles at room temperature in air-saturated aqueous solutions of poly(ethylene glycols) and poly(vinyl alcohols). Formation of An particles is substantially faster in the case of poly(ethylene glycols). In several systems, an intermediate is observed at the early stages of the formation of Au particles; it decays in a few minutes to form metal particles. The stability of the resulting Au colloids as well as the rates of reaction are dependent on the polymer molar mass. The kinetic observations are explained under the assumption that Au(III) complexes initially bound to pseudocrown ether structures of the poly(ethylene glycols) are reduced by the macromolecules.