Department of Civil Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711 103, West Bengal, India E-mail : supriyogoswami.ju@gmail.com, debabrata@civil.iiests.ac.in Manuscript received 15 November 2017, accepted 17 February 2018 The composite chrome tannery wastewater originates from tannery units and contains substantial quantity of slowly-biodegradable substances, which make it incompatible for conventional biological treat­ment like ASP. Therefore, Moving Bed Hybrid Bioreactor (MBHBR) can be selected for treating this type of wastewater, as it is capable to handle the wastewater containing slowly biodegradable substance. Looking into this matter, the present research study was undertaken to find out the performance of MBHBR system for treatment of composite chrome tannery wastewater. The MBHBR system was run under continuous mode of operation at different bio-carrier variations i.e. 50 g/L, 75 g/L and 100 g/L under 3(three) different HRT combinations viz. 8, 10 and 12 h. In this study, maximum 85% COD removal efficiency was observed for a bio-carrier concentration of 100 g/L, hydraulic retention time of 8 h and organic loading rate (OLR) of 7.5 kg/m3/day under an initial COD concentration of 2500 mg/L.