This study examines the performance of bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactor in treating simulated wastewaters containing 1,1,2,2-tetrachloroethane (TeCA). Reactors R1 (control) and R2 (containing TeCA) were operated at Hydraulic Retention Times (HRTs) of 36, 30, 24, 18 and 12h. The removal of TeCA decreased from 99.85% to 98.40% as the HRT was lowered down from 36 to 12h. The maximum TeCA dechlorination rate and the half velocity coefficient were 0.2d −1 and 18.58mg TeCA/l, respectively. The Organic Loading Rate (OLR) was varied from 1.5 to 3.1kg/m 3 /d to yield various substrate:co-substrate ratios and the overall removal of TeCA throughout this study was more than 99%. The average effluent TeCA concentration at optimum HRT (24h) and substrate:co-substrate ratio (100:1) was less than 0.1mg/l. The granules within the reactor were 0.1–3.2mm in size with a heterogeneous bacterial population.