The preparation of activated carbon from date stone treated with phosphoric acid was optimized using rotatable central composite design of response surface methodology (RSM). The chemical activating agent concentration and temperature of activation plays a crucial role in preparation of large surface area activated carbons. The optimized activated carbon was characterized using thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the larger surface area of activated carbon from date stone can be achieved under optimum activating agent (phosphoric acid) concentration, 50.0% (8.674 mol L-1) and activation temperature, 900 degrees C. The Brunauer-Emmett-Teller (BET) surface area of optimized activated carbon was found to be 1225 m(2) g(-1), and thermogravimetric analysis revealed that 55.2% mass of optimized activated carbon was found thermally stable till 900 degrees C. The leading chemical functional groups found in the date stone activated carbon were aliphatic carboxylic acid salt upsilon(C=O) 1561.22 cm(-1) and 1384.52 cm(-1), aliphatic hydrocarbons upsilon(C-H) 2922.99 cm(-1) (C-H sym./asym. stretch frequency), aliphatic phosphates upsilon(P-O-C) 1054.09 cm(-1), and secondary aliphatic alcohols upsilon(O-H) 3419.81 cm(-1) and 1159.83 cm(-1). (C) 2013 Elsevier Ltd. All rights reserved.