Villaseñor, J. Instituto de Química de Recursos Naturales, Universidad de Talca, Casilla 747 Talca, Chile.The photocatalytic degradation of pentachlorophenol on ZnO catalysts is reported. The studies were carried out in a conventional photoreactor at 298 K using 30 ppm of pentachlorophenol. Appropriate catalytic activity and high selectivity to mineralization products were found. A significant increase in the conversion was achieved at higher temperatures. No direct relationship between catalytic activity and specific area or bandgap was found.