Mesoporous carbon-ZrO2 composites (CZrX) were successfully synthesized by a direct sol-gel procedure. A large battery of experimental techniques is applied for sample characterization. ZrO2 nanoparticles were homogeneously distributed on the carbon supports and stabilized in the cubic phase. The interactions between organic-inorganic phases determine the formation of non-stoichiometric ZrOx oxides, the reduction of the ZrO2 band-gap values and the charge carriers' recombination, favouring the absorbance of visible light and the photocatalytic behaviour. The total mineralization of the dye and the simultaneous reduction of the toxicity are achieved. (C) 2017 Elsevier B.V. All rights reserved.