Abstract: This invention comprises a novel method for the preparation of metal hydrocarbonyls of metals of Groups 1b, 2b, 3b, 4b, 5b, 6b, 7b and 8 of the Periodic Table of the Elements and the attendant method for isolation of pure metals by the separation of a single metal as a metal hydrocarbonyl from any mixture and the subsequent decomposition of the metal hydrocarbonyl to metal powder. The methods of this invention are of particular value in recovering valuable metals in pure state from such sources as exhausted or poisoned metal-based catalysts, low grade ores, filter cakes or mining tailings. Gaseous metal hydrocarbonyl products of this invention also make possible isotope separation.