Olive-seed waste residue char was employed as the precursor for the production of activated carbons with KOH activation. The effects of activation time and activation temperature on porosity of the prepared carbons were studied. The products were characterized by N 2 adsorption at 77 K, using the BET, α s and Dubinin–Radushkevich methods while the adsorption capacity from liquid phase was demonstrated by the isotherms of methylene blue adsorption from aqueous solutions. In comparison with the commercial grade carbons, the activated carbons from olive-seed waste residue showed considerably higher surface areas and can be characterized as “super-activated carbons”. The pores of the produced carbons are composed of micropores at the early stages of activation and of both micropores and mesopores at the late stages. Surface area and the pore volume were found to increase with the degree of burn-off, i.e. the activation time and temperature. Methylene blue removal capacity appeared to be comparable to commercial products and even higher at high degrees of activation.