Activated carbon with BET surface areas in a narrow range from 2318 to 2474 m(2)/g was made by soaking the char made from corncob in a concentrated NaOH solution at NaOH/char ratios from 3 to 6: the mesopore volumes of the activated carbon were significantly changed from 21 to 58%. The relationships between pore properties (S-p, V-pore, V-micro/V-pore, D-p) and NaOH dosage were investigated. Comparisons between the methods of NaOH and KOH activation revealed that NaOH activation can suitably control the mesopore specific volume of the activated carbon. Elemental analysis revealed that the H/C and O/C values of the activated carbons of NaOH/char ratios from 3 to 6 were significantly lower. SEM observation of surface hole variation of the activated carbon ascertained that the reaction process was inner pore etching. Based on the above three measurements and experimental investigations, the assumption made by previous researchers, namely that NaOH and KOH produce similar results, was challenged. Furthermore, the adsorption kinetics was used to investigate the adsorption rate of an Elovich equation to determine the relationships between the adsorption behavior on larger molecules (dyes) and smaller molecules (phenols) and the pore structure of the activated carbon. (c) 2006 Elsevier Inc. All rights reserved.