This performance of an anaerobic baffled reactor (ABR) for the pre-treatment of the dyeing industry wastewater at the start-up phasewas investigated.The ABRs operational features and the influence of different hydraulic retention times (HRTs) on the profiles of the Oxidation Reduction Potential (ORP) and volatile fatty acid (VFA) was investigated.The ABR performed well in removing chemical oxygen demand (COD) and color from the wastewater at the start-up phase.Its efficiency in removing VFA decreased as the HRT was shortened, and the ORP kept under-165 mV.This indicates that the combined ABR process is suitable for pre-treating the dyeing industry wastewater, a good conditions was formed for the subsequent aerobic biodegradation due to ABR pre-treatment.