Photocatalytic panel reactor for the anaerobic photoreforming of waste aqueous effluents and the production of hydrogen as co-product characterized in that it comprises: - at least one flat panel comprising: o a shallow container and o a top transparent window, said top window being intended to face a source of light; - a bed composed of a photocatalyst material, comprising at least one photoactive semiconductor, immobilised therein, the bed being located on an irradiated surface of the flat panel; - a flow region located in the shallow container, said region being arranged so that a waste aqueous effluent flows through it and enters into close contact with the photocatalyst material immobilised in the bed; and - a sealing gasket disposed between the shallow container and the top transparent window, intended to ensure the tightness of the panel and its isolation from ambient air; - (i) gas outlet ports provided in the container, said outlet ports being connected through tubes to at least one gas-tight storage tank; or, alternatively, (ii) a recirculation circuit provided with: - a tank - at least one external pump intended to make the aqueous effluent recirculate from the tank to the container and then from the container back to the tank; and - a gas-liquid separation chamber, said gas-liquid separation chamber being connected through tubes to at least one gas-tight storage tank and comprised in an elevated part of the recirculation circuit. wherein - the photocatalyst material also contains at least one co-catalyst in the form of particles deposited on the surface of the photoactive semiconductor, said co-catalyst comprising: o metals, such as Cu, Fe, Co, Ni, Zn, Sn, Cr, Pb, Bi, Ag, Au, Pd, Rh, Ru, Pt, Ir, or Cd; o metal oxides, metal sulphides, metal phosphides and/or organometallic species; and o combinations thereof. - at least one flat panel comprising: o a shallow container and o a top transparent window, said top window being intended to face a source of light; o a shallow container and o a top transparent window, said top window being intended to face a source of light; - a bed composed of a photocatalyst material, comprising at least one photoactive semiconductor, immobilised therein, the bed being located on an irradiated surface of the flat panel; - a flow region located in the shallow container, said region being arranged so that a waste aqueous effluent flows through it and enters into close contact with the photocatalyst material immobilised in the bed; and - a sealing gasket disposed between the shallow container and the top transparent window, intended to ensure the tightness of the panel and its isolation from ambient air; - (i) gas outlet ports provided in the container, said outlet ports being connected through tubes to at least one gas-tight storage tank; or, alternatively, (ii) a recirculation circuit provided with: - a tank - at least one external pump intended to make the aqueous effluent recirculate from the tank to the container and then from the container back to the tank; and - a gas-liquid separation chamber, said gas-liquid separation chamber being connected through tubes to at least one gas-tight storage tank and comprised in an elevated part of the recirculation circuit. wherein - a tank - at least one external pump intended to make the aqueous effluent recirculate from the tank to the container and then from the container back to the tank; and - a gas-liquid separation chamber, said gas-liquid separation chamber being connected through tubes to at least one gas-tight storage tank and comprised in an elevated part of the recirculation circuit. - the photocatalyst material also contains at least one co-catalyst in the form of particles deposited on the surface of the photoactive semiconductor, said co-catalyst comprising: o metals, such as Cu, Fe, Co, Ni, Zn, Sn, Cr, Pb, Bi, Ag, Au, Pd, Rh, Ru, Pt, Ir, or Cd; o metal oxides, metal sulphides, metal phosphides and/or organometallic species; and o combinations thereof. o metals, such as Cu, Fe, Co, Ni, Zn, Sn, Cr, Pb, Bi, Ag, Au, Pd, Rh, Ru, Pt, Ir, or Cd; o metal oxides, metal sulphides, metal phosphides and/or organometallic species; and o combinations thereof.