Spectrophotometric determination of Ni(II) was carried out using picolinaldehyde-4-phenyl-3-thiosemicarbazone (PAPT) as a complexing/chromogenic reagent. The possibility of using a micellar system was explored to enhance the degree of detection and allow a more sensitive spectrophotometric method for the determination of nickel ions. The anionic surfactant Triton X-100 greatly enhanced the molar absorptivity and limit of detection relative to that observed with bulk water or an organic solvent. The linear calibration graphs were obtained for 0.5-2.0 mg L(-1) and 0.001-1.0 mg L(-1) of Ni(II) in aqueous and surfactant media, respectively. Using this approach, the limit of detection for the PAPT-Ni(II) complex (based on 3 sigma of blank absorbance/slope) was found to be 0.0008 mg L(-1) with a micellar enhancement reagent. The interference from over 50 cations, anions, and complexing agents was studied at 0.50 mg L(-1) of Ni(II); most metal ions can be tolerated in considerable amounts in aqueous micellar solutions.