Activated carbons were prepared from rice hull by one-step phosphoric acid activation in this work. The evolution of pore structure and surface chemistry in the activation temperature range of 170-450 °C was investigated through various characterization techniques. The results showed that the development of porosity (extent of activation) was negligible at activation temperature below 300 °C, and rapid evolution occurred in 300-400 °C. Porous activated carbon with bimodel pore structure (pore < 1 nm and pore > 1 nm) and BET surface area as high as 1295 m 2 /g was obtained at 450 °C. The ash contents of samples prepared in this study were in the range of 5-21%. The ash contents of carbons prepared in this study initially decreased from 21.03% to 4.89% with the change of temperature from 170 to 300 °C, then increased to 8.72% at 450 °C. Boehm titration results suggested that low activation temperature (6300 °C) benefits the formation of acidic surface groups. With the increase of activation temperature from 300 to 350 °C, the concentrations of strong, intermediate and weak acidic surface groups decreased from 2.23, 1.87, and 2.73 to 1.66, 1.32, and 2.16 mmol H + /g, respectively. Over 350 °C, the change of these groups were insignificant. FTIR results revealed the existence of carbonyl-containing, phosphorus-containing groups, and groups containing Si-O bond. The relative concentration of carbonyl-containing groups decreases with an increase in activation temperature, while that of phosphorus-containing groups follows the reverse trend. The content of Si-O decreased first, then slowly increased with the increase of activation temperature. Boehm titration and FTIR (Fourier transform infrared spectroscopy) results indicated that the surfaces of these carbons contain both temperature-sensitive and temperature-insensitive groups. The temperature-sensitive part consists mainly of carbonyl-containing groups, such as carboxylic groups, while the temperature-insensitive part is primarily phosphorus-containing groups and groups containing Si-O bond. This study demonstrated that carbon products with relative low ash content and high activation degree can be prepared from rice hull by H 3 PO 4 activation at suitable temperature.