Ethiopia gets vast amount of foreign exchange from the leather industry sector by exporting semi processed or finished leather product. Most tanneries in Ethiopia partially treat or do not treat their effluent before discharging it into the receiving water bodies therefore untreated leather effluent responsible for tremendous pollution of water resources in the country. Therefore the main objective of the study was to developing and evaluating the performance of sequencing batch reactor (SBR) for the treatment of sulfur rich tannery effluent in a case study of Modjo tannery. Sequencing batch reactor was used because it is a technology with high removal efficiency, easily expandable, simple operation and process which has the capability to receive shock organic loads and low capital costs. The treatment performance of SBR was assessed for selected parameters such as, BOD5, COD, TSS, TN, TP, NO3-, NH4, SO42-, TDS, TS and electrical conductivity based on APHA manual. The working condition of SBR was HRT, 48hr cycle, sludge age of 15 days temperature 20 0C and with optimum pH, EC and DO. The system showed high removal efficiency for sulfide( S2),which was 99.73% and good removal efficiency for BOD5 (86.77%), COD (95.7%), TSS (90.7%), TN (86.7%), TP (66.1%), NO3- (83.1%), SO4 (64.5%), TDS (58.7%), TS (68.4%) the achievement of high removal efficiency could be related to suitable working condition for the consortia of bacteria in each reactor while the concentration of NH4+showed increment from influent by 25%. Nitrate reducing sulfide oxidizing bacteria (NR-SOB) bacteria were isolated from anoxic reactor and their removal efficiency of nitrate and sulfide was evaluated. Out of 27 isolates of consortia two potential isolates were obtained with nitrate removal efficiency of 90% and 81.4% for isolate 22 & 26 respectively and sulfide removal efficiency of 98.4% for isolate 26 within an hour. Generally the SBR system showed significant removal of pollutants especially sulfide which could be related to the presence of high efficient sulfide oxidizer and nitrate reducer bacteria in anoxic condition. Therefore, it can be concluded that SBR is very effective secondary tannery effluent treatment method and it is recommended to apply it at large scale to overcome pollution problem of tannery industries by including other tertiary treatment method.rnKeywords: Sequencing batch reactor, wastewater treatment, NR-SOB consortia, Tannery effluent