Activated carbon from coconut shell was modified with sodium acetate at concentrations of 10% and 15%, and used in a fixed-bed column to study the adsorption of copper ions. Synthetic wastewater containing 258 mg/l of Cu was passed through plain activated carbon and modified activated carbon. Plain activated carbon was able to adsorb 20 mg of Cu, and activated carbon modified by treatment with 10% sodium acetate adsorbed 33 mg of Cu. The highest adsorption capacity was found for the activated carbon modified by treatment with 15% sodium acetate, which adsorbed 45 mg of Cu; i.e. 2.2 times as much as the plain activated carbon. After regeneration with 0.71 M NaOH, the activated carbon modified by treatment with 15% sodium acetate was able to adsorb 60 mg of Cu; i.e. three times as much as the plain activated carbon.