The effects of activation time and activation temperature on the yield and the adsorptive capacity towards iodine were studied. The yield and the quality of the activated carbon prepared by using H3PO4 were compared with that prepared from date stones using the same equipment, and under similar conditions by using ZnCl2 as an oxidizing agent. The iodine number for the produced activated carbon was higher when H3PO4 was used, compared to that when ZnCl2 was used. The yield obtained when H3PO4 was used was lower than the yield when ZnCl2 was used. The iodine number increases significantly with increasing the activation temperature.