Hydrogen sulphide (H 2 S) is one of the most problematic contaminants in biogas. In this study, a biotrickling filter with a working volume of 2.4L and packed with polypropylene Pall rings was tested for its ability to remove H 2 S from biogas under anoxic conditions. The influence of the H 2 S inlet concentration, nitrate feeding regime (manual and controlled) and liquid flow rate on the elimination capacity of the biotrickling filter was studied. The results indicate that 99% of the H 2 S was removed for H 2 S inlet loads lower than 120gSm −3 h −1 when using controlled nitrate feeding by ORP.