A new and simple method for the preconcentration and spectrophotometric determination of trace amounts of nickel was developed by cloud point extraction (CPE). In the proposed work, dimethylglyoxime (DMG) was used as the chelating agent and Triton X-114 was selected as a non-ionic surfactant for CPE. The parameters affecting the cloud point extraction including the pH of sample solution, concentration of the chelating agent and surfactant, equilibration temperature and time were optimized. Under the optimum conditions, the calibration graph was linear in the range of 10-150 ng mL-1 with a detection limit of 4 ng mL-1. The relative standard deviation for 9 replicates of 100 ng mL-1 Ni(II) was 1.04%. The interference effect of some anions and cations was studied. The method was applied to the determination of Ni(II) in water samples with satisfactory results.