Solid and liquid substrates, such as soil and solvents having radioactive metals or hazardous non-radioactive metals are decontaminated with the aid of cyanide ion generated in-situ to form co-ordination compounds with the unwanted metal contaminants. Cyanides are prepared by introducing into an ammoniacal liquid-containing slurry of a contaminated soil, or other solid or liquid substrate, a refrigerant compound, such as a hydrochlorofluorocarbon which produces ammonium cyanide, which in-turn forms a complex with the hazardous metal contaminant for separation with the ammoniacal liquid. The process may also utilize solvated electrons to at least partially dehalogenate a perhalogenated refrigerant like diclorodifluoromethane (R-12). Process avoids exposure to potentially hazardous cyanides through in-situ generation, while simultaneously destroying unwanted refrigerants which are potentially harmful to Earth's ozone layer.