In this study, the use of activated carbon prepared from orange (Citrus sinensis L.) pulp by chemical activation has been investigated as an ideal alternative to the current expensive methods of removing phosphate ions. The effects of initial pH, initial concentration, contact time, temperature and other ions on adsorption were studied. The surface area and micropore volume of the obtained activated carbon were 1779.48 m(2) g(-1) and 1.1 cm(3) g(-2), respectively. The results indicated that the adsorption of phosphate ions followed a pseudo-second-order kinetic model and fitted the Langmuir and Temkin isotherm models better than other isotherm models. The maximum adsorption capacity obtained from Langmuir equation was 4.61 mg g(-1). The calculated thermodynamic parameters were showed that the adsorption of phosphate ions onto activated carbon was feasible, spontaneous and exothermic at 298-318 K. The results suggest that the activated carbon prepared from orange pulp has potential in remediation of phosphate ions contaminated waters.