We report on the preparation of biomass-based activated carbons by the steam physical activation and KOH chemical activation methods. In addition, we also investigate their adsorption performance. By adjusting the reaction parameters, different carbon materials are prepared from corn residues and characterized using instrumental analyses such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Brunauer-Emmett-Teller (BET). It is found that the synthesized activated carbons exhibit high surface area (1600 m(2) g(-1)) and large pore volume (2.01 cm(3) g(-1)). Furthermore, the high methylene blue and iodine adsorption value and a considerable CO2 uptake (exceeding 1.5 mmol g(-1)) are attained with the activated carbons, showing their potential usage for the CO2 adsorbent. (c) 2012 Elsevier Ltd. All rights reserved.