The effect of activation temperature on the textural and chemical properties of activated carbons prepared from pistachio-nut shells by potassium hydroxide activation was studied. Relatively high activation temperature was required to develop high porosities. However, too high an activation temperature resulted in the burn-off of the carbon structures and the widening of micropores to meso- and macropores. The microstructures and microcrystallinities of the carbons prepared were examined using a scanning electron microscope and a powder X-ray diffraction analyzer, respectively, while the Fourier transform infrared spectra indicated the changes in the surface functional groups that were formed during the different preparation stages. (C) 2003 Elsevier Inc. All rights reserved.