Under UV light, phenol degrades on the surface of Y2O3, an insulator, and the degradation follows first-order kinetics, depends linearly on the light intensity and slows down with pH. The efficiency of degradation is higher with UV-C light than with UV-A light. While particulate anatase TiO2, ZnO, ZnS, Fe2O3, CuO, CdC, and Nb2O5 individually photodegrade phenol, each semiconductor shows synergism when present along with Y2O3, indicating electron-transfer from phenol adsorbed on Y2O3 to the illuminated semiconductors. (C) 2009 Elsevier B.V. All rights reserved.