Abstract: Process for treating oxidized ores with a manganiferous matrix to recover the small quantities of copper, nickel and cobalt, which consists of attacking the aforementioned ore by means of an aqueous solution of H.sub.2 SO.sub.4 with the simultaneous injection of sulfur dioxide, at a temperature which does not exceed boiling point of the medium, at a pH less than 1.5; introducing an alkaline sulfide to precipitate the copper, nickel and cobalt sulfides in the suspension resulting from the attack; and separating by sulfides and the residue by flotation. The process is applicable to attacks on manganiferous nodules obtained from ocean beds as well as to attacks on land manganiferous matrix oxidized ores.