Abstract: Benzene is one of the biggest challenges of groundwater pollution due to of its toxicity, motility in the environment and solubility in groundwater. Granular Dead Activated Sludge (GDAS) was investigated as low-cost and locally available as sorbent material for removing benzene from aqueous solution. The experimental results show that the removal efficiency has improved with increasing both of GDAS amount and the time of contact and decreasing the initial concentration of contaminant. Langmuir and Freundlich isotherm model give a good fitting for sorption process with high determination coefficient >0.998. The parameter of this model shows a favorable sorption for removing benzene by GDAS. Intra-particle diffusion model data fitting shows two separate regions, the first severe portion attributed to the immediate sorption step and another portion is the intraparticle diffusion rate is dominated. The parameters of model illustrate the external mass transport mechanisms must be considered with intra-particle diffusion.