In this study, nano-TiO2-supported activated carbon (TiO2/AC) was developed for the microwave (MW) degradation of an azo dye, methyl orange (MO), selected as a model contaminant in aqueous solution. The effects of selected process parameters such as supported TiO2 content, MW irradiation time, initial MO concentration, catalyst dose, and solution pH on the degradation were assessed in detail. The results showed that the supported TiO2 on AC could be excited resulting in the production of hydroxyl radical (center dot OH) in aqueous solution under MW irradiation, which significantly enhanced the performance of AC/MW process for the degradation of MO. Also, the supported-TiO2/AC displayed higher catalytic activity than AC alone under MW irradiation. By comparison, the supported-TiO2/AC/MW process exhibited several advantages, including high degradation rate, short irradiation time, no residual intermediates and no secondary pollution. Hence, it shows to be a promising technology for the destruction of organic contaminants in dye treatment applications. (C) 2012 Elsevier B.V. All rights reserved.