In this paper nanosized Co3O4/CeO2 was successfully synthesized by a simple hydrothermal method and was applied as catalyst in catalytic ozonation of phenol in solution. The observed results show that nanoparticles have a pleasant special surface. Ozonation experiments indicate that the nanoparticles present a certain catalytic effect on the degradation of phenol and a remarkable acceleration on the chemical oxygen demand removal. Further investigations reveal that a mechanism of solid-liquid interface reactions exists in this system.