The treatment of gaseous trichloroethylene (TCE) by biotic and abiotic removal mechanisms in a sequential (biological/chemical) reactor system was investigated. The reactor system consisted of a granular anaerobic mixed culture packed biofilter followed by an elemental iron metal (Fe(O)) packed column in series. The effect of empty bed contact time (EBCT) and influent TCE concentration on the TCE removal performance of the system were investigated. In order to determine the effect of EBCT on the TCE removal performance of the system and the optimum EBCT for this system, EBCTs from 0.25 to 2.5 h were applied. The system was fed with 170.6 ± 28.5 ppmv of average influent TCE concentration, 5000 ppmv of H2, 2000 ppmv of CO2 and 6000 ppmv of N2. Optimum EBCT for the system was determined as 1 h. The TCE removal performance at this EBCT was 31.0 ± 2.8% in the biofilter, 80.9 ± 6.9% in the Fe(O) packed column and 86.7 ± 5.2% in the overall system. Only ethylene and ethane were detected in the effluent of the system as reduction by-products. In addition, the performance of the system was not altered between the initial TCE concentrations of 150 and 650 ppmv at 1h of EBCT. © TÜBITAK.