Abstract: A process for the treatment of a complex manganese ore, wherein it comprises the following stages:(a) crushing the ore,(b) subdividing the crushed ore into a first part and a second part,(c) preparing the first pulp from the first part of the crushed ore,(d) reacting the first pulp with a reducing agent to obtain a manganous sulphate solution,(e) separating the liquid phase constituted by the thus obtained manganous sulphate solution from the solid phase of the thus treated first pulp,(f) preparing a second pulp from the second part of the crushed ore,(g) subjecting the second pulp to a solubilization treatment of the nickel, copper and cobalt by reacting it hot with sulphuric acid and the manganous sulphate solution obtained in stage (e),(h) separating the liquid phase and the solid phase of the thus treated second pulp, and(i) recovering the nickel, copper and cobalt from the liquid phase separated in stage (h).