Wastewater commonly contains significant amount of inorganic ions. In this work, the effect of the existence of different inorganic ions including Ni3+, Cu2+, Fe3+, SO42-, Cl- in the synthetic wastewater was investigated. Nano structured Fe/TiO2 photo catalyst was synthesized by the sol-gel method. The experiments were carried out under UV light, in the presence of H2O2 (30%), and the concentration of phenol in wastewater was 200 ppm and in regard to ion it is 1 mM. The SO42-, Cl- (both of them from Na+ salts) were adsorbed on the surface of TiO2 and inhibited photo catalysis. The anions reacted with and thus inhibited the photo catalyst degradation. The Ni3+, Cu2+, Fe3+ cations were from NO3- salts , and among them Cu2+ enhanced the photo catalyst degradation which can be attributed to the electron scavenger effect that prevents the recombination of electron-hole pairs.END