Biological control of odor gases has gained more attention in recent years. In this study, removal performance of a vertical bio-trickling filter inoculated with bacteria and fungi was studied. Bacteria and fungi were isolated from activated sludge in a sewage treatment plant. By adopting "three step immobilization method", the bio-trickling filter could degrade pollutant immediately once hydrogen sulfide (H2S) passed. The optimal empty bed resident time was 20 s. The optimal elimination capacity was about 60 g H2S m(-3) h(-1) with removal efficiency of 95%. And the maximum elimination capacity was 170 g H2S m(-3) h(-1). Pressure drop was ranged between 5 and 15 mm H2O per bed over the whole operation. Removal efficiency was not affected obviously after terminating nutrient supply. The bio-trickling filter could recover back after shut down H2S gaseous and liquid supplies simultaneously. Microbial community structure in the bio-trickling filter was not changed significantly. Combining bacteria and fungi would be a better choice for inoculation into a bio-trickling filter because of the quickly degradation of H2S and rapid recovery under shut-down experiment. This is the first study attempting to combine bacteria and fungi for removal of H2S in a bio-trickling filter. (c) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.