In this study, activated carbon was produced using three different chemical reagents (KOH, NaOH and LiOH). The BET surface area of the activated carbon obtained by using KOH was found to be 588 in and it was selected as the most suitable one for heavy metal adsorption from an aqueous solution. During the experiments, an investigation was carried out to examine the effects of parameters, such as the contact time, the aqueous solution pH, the activated carbon dosage, the initial metal concentration and the aqueous solution temperature, on adsorption. It was established that activated carbon exhibited an adsorption capacity in the order of Pb(II > Cu(II > Ni(H). The adsorption isotherms of Pb(II), Cu(II) and Ni(II) ions were established to be in accordance with the Langmuir and Freundlich isotherms. In the adsorption process, the enthalpy variations were found to be -20.4 kJ/mol, -17.2 kJ/ mol and - 17.9 kJ/ mol, respectively.