Decolorization of anthraquinone dye Reactive Blue 4 (RB4) in an aqueous solution was investigated by using Fe-ball clay (Fe-BC) as heterogeneous catalyst. The best reacting conditions were found to be 0.80 wt.% of iron ions loading on ball clay (BC) when the dosage of catalyst is 5.0 g L-1 with initial pH of 3.0. [H2O2](0) of 8 mM, [RB4](0) of 50 mg L-1 at temperature 30 degrees C. Under these conditions, 99% decolorization efficiency of RB4 was achieved within 140 min reaction time. The results indicated that Fe-BC has proven to be a superior heterogeneous catalyst for decolorization of RB4 in an aqueous solution. (C) 2011 Elsevier B.V. All rights reserved.