The production of activated carbon from polystyrene waste is tested in order to limit its negative environmental impact through conversion to value added products. For this purpose modification of the precursor, slow pyrolysis and subsequent activations, i.e. high temperature steam activation and low temperature air oxidation, are applied. The physical/chemical properties as well as adsorption capacities of obtained activated carbons (ACs) towards Ni(II) removal in aqueous solutions are explored. Steam activated carbon S-ACMPS performs superior in Ni(II) removal at applied circumstances. Ni(II) adsorption by this AC has been investigated using different process parameters and occult' through cation exchange mechanism optimal at pH range of initial solution of 4-8. Several reaction based kinetic models, i.e. pseudo-first, pseudo-second and Elovich models, and intra-particle diffusion model, are applied on experimental data. The adsorption kinetics of Ni(II) is best approximated by a pseudo second-order model. The equilibrium adsorption data best fits the Langmuir adsorption isotherm. Calculated maximum adsorption capacity for S-ACMPS is 40.8 mg g(-1). (C) 2016 Elsevier B.V. All rights reserved.