Abstract: A process for producing molybdenum compounds, from spent molybdenum catalyzers, industrial residues and metal alloys, particularly an integrated process for reclaiming molybdenum, vanadium, nickel, cobalt, aluminum and other metals, starting with the treatment of exhausted catalyzers, industrial residues and metal alloys, principally from petroleum de-sulfurization catalyzers; the molybdenum trioxide is obtained by precipitation of ammonium octamolybdate and its calcination. Starting from molybdenum trioxide, other compounds derived from molybdenum can be obtained, as sodium molybdate, molybdenum disulfite and ammonium molybdate.