In the present article, modified IR-120 Amberlite resin was used as sorbent for preconcentration trace amounts of nickel ions. Nickel ion was adsorbed quantitatively onto IR-120 Amberlite resin that modified with 5-)4-dimethyl amino-benzylidene)-rhodanin in the pH range of 5.5-7.0. The adsorbed nickel ions were eluted with 5.0 mL of 3 mol L-1 nitric acid solutions and nickel was determined by flame atomic absorption spectrometry. The linear rang was 0.62 ng mL(-1) and 18.0 mu g mL(-1) in initial solution. Detection limit was 0.141 ng mL(-1) in initial solution (3S(b1), n=7) and preconcentration factor was 160. Relative standard deviation for the 7 replicated determination of 4.0 mu g mL(-1) of nickel solution was +/- 1.3%. The effects of the experimental parameters, including the sample pH, flow rates of sample and eluent solution, eluent type, breakthrough volume and interference ions were studied for preconcentration of Ni(II) ions. The method was successfully applied for separation and determination of nickel ions in water and standard samples.