The aqueous phase photocatalytic degradation of Sirius Gelb GC used in the textile industry, was investigated. In order to optimize the working pH, three different dye solutions were prepared at pH 3.5; 7.0 and 11.0. One hundred cubic centimeter portions of the solution were irradiated with a low pressure UV lamb in the absence and presence of catalysts TiO2, or Ag loaded-TiO2. In all conditions, the samples withdrawn from the reactor were centrifuged and separated from the catalyst and degradation percentages were calculated from the measurement of the residual dye concentrations, spectrophotometrically. The optimum pH, which provides the best degradation ratio was found to be 3.5 for the dye. At the same pH, it was found that silver loaded catalyst is more effective than neat TiO2 catalyst. The silver loading dramatically reduced the irradiation time from 20 min to 8 min for Sirius Gelb GC. However, the catalytical behavior of the both the catalysts was also investigated in heavy salt media such as simulated wastewater and in a river fluent. Pooled standard deviation (S-pooled) of the repeated measurements in all conditions is 0.615 for N = 47 and 38 degrees of freedom. Confidence limit of the method is 98.8 +/- 0.2 in 95% confidence level. (C) 2004 Elsevier B.V. All rights reserved.