p-chlorobenzaldehyde-4-(2’-carboxy-5’-sulphophenyl)-3-thiosemicarbazone [p-CBCST] is spectrophoto-metric reagent for nickel (II) in DMF. The metal ion reacts with p-Chlorobenzaldehyde-4-(2’-carboxy-5’-sulphophenyl)-3- thiosemicarbazone [p-CBCST] forming a dark green colored complex in the pH range 4.5-5.0. The complex shows maximum absorption at 315 nm. The molar absorptivity found to be 6.090×103lit. mol.-1 cm.-1. The solid complexes have been isolated and characterized using elemental analysis, UV, IR, NMR spectra. p-CBCST is found to be a selective and strong chelating agent for nickel. The results deduced from Job’s method of continuous variation, the mole ratio and the slope ratio method showed that metal:ligand ratio in the complex to be 1:2. The stability constant of the complex found to be 5.551 × 1010.