NOVELTY - Anodic (intended for fuel oxidation) and cathodic (intended for oxygen reduction) electrocatalysts are made of mono- and plurimetallic clusters supported on carbon nitrides.    USE - The electrocatalysts are used in Polymer Electrolyte Membrane Fuel Cells (PEFC) and Direct Methanol Fuel Cells (DMFC) and in hydrogen (H2) electrogenerators.    ADVANTAGE - The electrocatalysts allow a fuel cell operating at low temperature to produce an adequate amount of current at acceptable potentials.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) synthesis of materials having a controlled metallic composition based on clusters of mono- plurimetallic carbon nitrides supported on ceramic materials based on oxides, comprising preparing a first precursor, subjecting the precursor to thermal treatments, and activating the resulting product, in a chemical and/or in electrochemical way; and    (2) method for the preparation of the precursor through sol-gel reactions by mixing two distinct solutions indicated as A and B, where solution A is made of an organic solvent (OS), an organic binder (OB) and one or more compounds containing a transition metal coordinated by halides such as chlorine, bromine or iodine, such as, HAuCl4, H2TrCl6, H2PtCl6, Li2PdCl4, (NH4)2IrCl6, (NH4)2OsCl6, (NH4)PdCl4, (NH4)2PdCl6, (NH4)2PtCl4, (NH4)2PtCl6, (NH4)3RhCl6, (NH4)2RuCl6, KAuCl4, KPt(NH3)Cl3, K2PdCl4, K2PtCl4, K2PdCl6, K2PtCl6, K2ReCl6, K2RhCl6, K2H2IrCl6, K2H2OsCl6, K3IrCl6, K3H3RuCl6, Na2IrCl6, Na2OsCl6, Na2PdCl4, Na2PtCl6, Na3RhCl6, CrCl3, IrCl3, FeCl3, NiCl2, OsCl3, PdCl2, PtCl2, PtCl4, RhCl3, RuCl3, ReCl5, SnCl4, VCl3, VCl4, WCl4, WCl6, ZrCl4 and others, and solution B is constituted by an organic solvent (OS), an organic binder (OB) and one or more compounds containing complexes of a transition element where there are ligands like cyano, isocyano, thiocyano, amino and amido groups, and where cyanometallates can be KAg(CN)2, KAu(CN)2, K2Ni(CN)4, K2Pd(CN)4, K2Pt(CN)4, K3Co(CN)6, K3Cr(CN)6, K3Fe(CN)6, K3Mn(CN)6, K2Pt(CN)6, or K4Ru(CN)6.    DESCRIPTION OF DRAWING(S) - The figure schematically shows polarization curves of the MEAs prepared with PtNi600 and the PtFe900 materials, together with the commercial reference.