The aim of this study is to investigate new catalyst systems for the oxidative degradation of chlorophenol (CP) derivatives that have been classified as first-degree toxic pollutants. Oxidative degradation and degradation products of chlorinated phenols, namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol, are discussed in detail. Homogenous catalyst systems Fenton [Fe(II)/H(2)O(2)) and Fenton-like [Cu(II)/H(2)O(2) and V (IV)/H(2)O(2)] methods were employed at higher CP concentrations (1 x 10(-2) mol/L). Heterogeneous catalyst systems titanium dioxide [TiO(2)/UV) and silver loaded titanium dioxide [Ag-TiO(2)/UV] processes were also investigated at lower concentrations. Chemical oxygen demand (COD), which is defined as oxygen equivalent of organic matter before and after degradation system was determined.