Crofton weed was converted into a high-quality activated carbon (CWAC) via microwave-induced CO2 physical activation. The operational variables including activation temperature, activation duration and CO2 flow rate on the adsorption capability and activated carbon yield were identified. Additionally the surface characteristics of CWAC were characterized by nitrogen adsorption isotherms, FTIR and SEM. The operating variables were optimized utilizing the response surface methodology and were identified to be an activation temperature of 980 degrees C, an activation duration of 90 mm and a CO2 flow rate of 300 ml/min with a iodine adsorption capacity of 972 mg/g and yield of 18.03%. The key parameters that characterize quality of the porous carbon such as the BET surface area, total pore volume and average pore diameter were estimated to be 1036 m(2)/g, 0.71 ml/g and 2.75 nm, respectively. The findings strongly support the feasibility of microwave heating for preparation of high surface area porous carbon from Crofton weed via CO2 activation. (C) 2014 Elsevier B.V. All rights reserved.