The main aim of this research was the experimental study at lab scale to check the absorption technology for the in situ removal of H2S from biogas during anaerobic digestion process. The reagent FeCl3, was used to check the removal efficiency of H2S produced from dairy manure during anaerobic bioconversion process. The experiments were conducted Under mesophilic conditions. The composition of biogas was analyzed by gas chromatography analyzer equipped with flame photometer and thermal conductivity detectors. Experimental results under the same conditions demonstrate that high concentration of H2S ill the form of FeS can be removed totally from the biogas using FeCl3 dosing with in anaerobic batch digester.