AbstractIncorporation of iron (a few percent) into RuS2(ΔEG= 1.85 eV) changes the energy gap to ΔEG= 1.1 eV. The resulting n‐type compound, which can approximately be described by “Ru1‐xFexS2”, is able to evolve oxygen and chlorine from aqueous electrolytes utilizing visible and near infrared light under energy gain with high quantum efficiency (23% to 60%). — Oxygen and chlorine evolution, mediated by infrared light, is found clearly below the respective redox potentials. Under such conditions of energy conversion the electrode does not indicate signs of photocorrosion. At more extreme electrode potentials traces of a ruthenium tetroxide species are observed — Attempts are made to correlate the (inhomogeneous) distribution of iron in Ru1‐xFexS2electrodes with photocurrent spectra and scanning laser spot current patterns. — Experiments show that the electrode surface is subject to chemical changes during the photoreaction with water. They are investigated by means of capacity measurements, dynamic current voltage sweeps, and systematical variations of redox potentials in the electrolyte. — A model is presented which accounts for the role of iron in this compound and which explains its photoelectrochemical advantages co