Waste apricot supplied by Malatya apricot plant (Turkey) was activated by using chemical activation method and K2CO3 was chosen for this purpose. Activation temperature was varied over the temperature range of 400-900 degrees C and N-2 atmosphere was used with 10 degrees C/min heat rate. The maximum surface area (1214 m(2)/g) and micropore volume (0.355 cm(3)/g) were obtained at 900 degrees C, but activated carbon was predominantly microporous at 700 degrees C. The resulting activated carbons were used for removal of Ni(H) ions from aqueous solution and adsorption properties have been investigated under various conditions such as pH, activation temperature, adsorbent dosage and nickel concentration. Adsorption parameters were determined by using Langmuir model. Optimal condition was determined as; pH 5, 0.7 g/10 ml adsorbent dosage, 10 mg/l Ni(H) concentration and 60 min contact time. The results indicate that the effective uptake of Ni(II) ions was obtained by activating the carbon at 900 degrees C. (c) 2005 Elsevier B.V. All rights reserved.