Photo-Fenton oxidation process followed by cobalt ferrite nanoparticles was applied for the degradation of phenol from aqueous solution. The physicochemical properties of cobalt ferrite nanoparticles synthesized by hydrothermal method, was characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). A batch study was conducted to optimize parameters such as pH (2-5), hydrogen peroxide concentration (0-1 mmol/L), catalyst concentration (0.1-0.5 g/L) and temperature (35-55 ºC) governing the photo-Fenton process. The results indicated that the optimum conditions for almost complete conversion of phenol was obtained under the following operating conditions: UV radiation of 60 watt; a pH of the aqueous solution of 3; a dose of 0.3 g catalyst/L, a hydrogen peroxide concentration of 0.3 mmol/L and temperature of 45 ºC for a solution containing 100 ppm of phenol. The results showed a significant dependence of the photo catalytic degradation of phenol on the functional parameters.