Abstract: The present research investigated the arsenic removal performance of prepared and commercial crab shell chitosan by adsorption filtration method. The ability of chitosan to remove arsenic from prepared arsenic contaminated solution was examined by Atomic Absorption Spectrometry (AAS). It is found that the saturation volume of prepared chitosan for l0 mg L-1 As3+/As5+ solution was 8.55 L and its arsenic removal capacity was 6244.2 mg kg-1. For commercial chitosan, the saturation volume for low and high molecular weight chitosan was 1.3 and 0.45 L and their arsenic removal capacity were 461.8 and 149.5 mg kg-1, respectively. The FT-IR study also confirmed that prepared chitosan’s arsenic removal capacity was higher than that of low and high molecular weight commercial chitosan due to the free amino group.