Filing Date: 2002-06-06.-- Priority Data: ES P 0101328 (2001-06-07)The method involves the following steps: a) leaching said IGCC ashes with an extracting agent selected amongst water, an aqueous solution of an acid and an aqueous solution of a base in order to solubilize all or part of the Ge contained in said IGCC ashes; b) separating the solid and liquid phases in the solution or suspension resulting from step a) into a solid phase (S1) and a liquid phase (L1) which contains the Ge and c) recovering the Ge in said liquid phase (L1). The inventive method makes it possible to upgrade the IGCC ashes by recovering the Ge and, optionally, other valuable metals, e.g. Ga, V and/or Ni.