This laboratory study investigates the performances of coconut shell waste-based activated carbon (CSBAC) in removing 4-chlorophenol (4-CP) from contaminated water. To improve its removal for target compound, the surface of CSBAC was modified with TiO2, NaOH, and/or HNO3. Under optimized conditions at the same initial concentration of 25mg/L, the NaOH-treated CSBAC could remove 91% of 4-CP, compared to the HNO3-oxidized CSBAC (60%) or the TiO2-coated CSBAC (72%). Although the NaOH-treated CSBAC could remove 91% of 4-CP, the adsorption treatment using this adsorbent alone was unable to meet the effluent limit of lower than 1mg/L. Therefore, subsequent biological processes are required to complement the removal of 4-CP from wastewater.