Due to increased public awareness of pollution problems, the consumption of activated carbon is increasing gradually year by year. In order to properly remove pollutants from drinking water and wastewater, it is necessary that technologies be developed for producing activated carbon from materials easily available. The objectives of this study were to develop a process for manufacturing activated carbon from agricultural wastes (rice shells, peanut shells, cotton seed shell and saw dust) and measure and compare the iodine number (mg/g), B.E.T. (m(2)/g), ash content (%), pore size distribution (PSD), COD removal ability (%) and NH3-N removal ability (%) of the manufactured activated carbon to commercially available forms. Agricultural wastes based activated carbon were manufactured using the steam-reaction method. A rotary kiln type furnace was used for both carbonization and activation. The optimum operating temperature for carbonization and activation were 650 ℃ and 880 ℃, respectively. With these conditions, the iodine number of activated carbon was 1089.6 mg/g, and the B.E.T. surface area was log, 1091 m(2)/g. Specifically, wastewater removal efficiency of COD was 50.4% for 200 ppm of AOS (Alpha-Olefin-Sulfonate : surfactants used in detergents) concentration, and NH3-N removal efficiency was 27.1% for 10 ppm of original NH3-N concentration.