An investigation of several agricultural wastes (almond shell, hazelnut shell, walnut shell and apricot stone) revealed that their suitability for granular activated carbon production is not determined by material specific (elemental composition) but type-specific features. Granular activated carbons were evaluated for their physical (attrition, bulk density), chemical (elemental composition, % weight loss), surface (surface area, surface chemistry) and adsorption properties (iodine number, phenol and methylene blue adsorption). Pyrolysis temperature and activation time with ZnCl2 had influence on the phenol and methylene blue adsorption capacities of especially for the activated carbons produced from hazelnut and walnut shells. Adsorption isotherm data were fitted to both Langmuir and Freundlich models. The following order of suitability of raw materials for activated carbon production was established: hazelnut shell > walnut shell approximate to apricot stone > almond shell. (C) 2003 Elsevier Inc. All rights reserved.