CuO particles were synthesized by a hydrothermal method and used to activate Oxone for advanced oxidation of phenol in aqueous solution. The effects of several parameters on the degradation efficiency of the process were investigated. The as-prepared catalyst exhibited high activity in degradation of phenol and 100% decomposition and 86% TOC removal could be achieved in 60 min at the optimum conditions. Moreover, the catalyst was demonstrated to have good stability and reusability. Radical quenching studies were conducted to classify the type of active radicals present in the reaction and X-ray photoelectron spectroscopy (XPS) was applied to investigate the transformation of the chemical state of copper. According to the experimental results, a reasonable mechanism was proposed to interpret the catalytic process. (C) 2011 Elsevier B.V. All rights reserved.