An environmentally sound process is described for the remediation of waste materials and oxides of metals that allows the separation, recovery and decontamination of metals. The method includes chemically reducing essentially all of a reducible toxic and potentially hazardous metal oxide of a metal-containing composition. A metal-containing composition is directed into a molten bath, including a first reducing agent which, under the operating conditions of the molten bath, chemically reduces a first metal oxide of a metal in the metal-containing composition to form a bath-soluble transient second metal oxide. A second reducing agent is directed into the molten bath. The second reducing agent, under the operations of the molten-bath, chemically reduces the second metal oxide, provided that the second reducing agent has a Gibbs free energy lower than that of the second metal oxide. The rate at which the second reducing agent is directed into the molten bath, relative to the rate at which the metal-oxide of the metal-containing composition is directed into the molten-bath, is sufficient to cause essentially all subsequently formed second metal oxide to dissolve in the molten bath, thereby chemically reducing essentially all of the metal oxide of the metal-containing composition. This indirect reduction technology can remediate a variety of materials, including ash metal-contaminated municipal waste, vitreous stag-like materials and spent metal catalysts, while allowing the recovery of remediable metals.