Abstract This work aimed to examine an iron pillared inter-layered clay as catalyst of the photo-Fenton process to oxidize phenolic compounds. The effect of the number of chlorine atoms substituted onto the ring was also studied. The selected clay was bentonite and the phenolic compounds were phenol, 4-chlorophenol and 2,4,6-tricholorophenol. The catalyst was synthesized by ionic exchange and characterized by X-ray diffraction, N2 physisorption, atomic absorption and X-ray photoelectron spectroscopy. In addition to the chlorine presence, the effect of other variables like initial concentration of H2O2 and catalyst loading was also evaluated. It was found that the highest 4-chlorophenol removal (94%) by degradation and mineralization is attained when using the stoichiometric amount of H2O2 and 0.8kg/m3 of catalyst. It outstands the fact that no pH adjustment was required at any moment in the experiment. Regarding the presence of chlorine in the pollutant structure, it was concluded that it significantly favors the degradation of the phenolic compound.