Low cost-high availability materials (pet coke, charcoals, lignite and used tire char), not extensively investigated in the past, were chemically activated with KOH. Produced activated carbons demonstrated high adsorption capacities both in the gas and liquid phase as exemplified by N-2 and methylene blue adsorption experiments and the application of BET and Langmuir equations and the DR method. An exception was the tire char, which was found to be most suitable for liquid phase rather than gas phase applications. From the discussion of the results it was concluded that some properties of the starting materials (crystallite size, reactivity and pore accessibility) are affecting the activation mechanism and if determined can form a basis for selecting the most suitable raw material for activation with KOH. Well-established experimental methods are proposed for the estimation of these properties. (c) 2004 Elsevier B.V. All rights reserved.