The new catalytic decoloration of C.I. Acid Red 3R with electro-coagulation (EC) method assisted by cobalt phosphomolybdate modified kaolin has been studied. The result showed that this process could effectively remove the C.I. Acid Red 3R contained in wastewater and its color removal efficiency could reach up to 98.3% in 7 min. The kinetics of the catalytic decolorization of Acid Red 3R was also studied. The decolorization reaction order was dependent on the initial concentration [R](0) with respect to the concentration of C.I. Acid Red 3R. At lower [R](0) the order was first, which then decreases with increasing [R](0). The operating parameters such as initial pH, current density and temperature were also investigated. A possible reaction mechanism was proposed. (c) 2006 Elsevier B.V. All rights reserved.