In this study, activated carbon prepared from hazelnut husk (HHAC) using zinc chloride as chemical activating agent was characterized by FT-IR spectroscopy, BET surface area, Boehm titration, SEM and elemental analyses. During adsorption from aqueous solution of methylene blue (MB) studied by the batch method, effects of many variables, including solution pH, agitation time, temperature and initial concentration were investigated. It was established that MB adsorption reached equilibrium at 120 min at pH 7.0 as the appropriate value and is more compatible with Langmuir adsorption isotherm with respect to Freundlich. MB adsorption capacity of HHAC was found to be 476.2 mg g(-1) and MB adsorption kinetics corresponds well with pseudo second order model. Thermodynamic studies revealed that MB adsorption is a spontaneous and endothermic process. (C) 2014 Elsevier B.V. All rights reserved.