Trace amounts of nickel in sea water and common salt were determined by atomic absorption spectrophotometry in conjunction with solvent extraction technique. Nickel reacted with 5-nitro-salicylaldehyde-4-phenyl-3-thiosemicarbazone (NSPS) to form a complex, which was extracted into methyl isobutyl ketone. The separated organic phase was sprayed into an acetylene-air flame. The optimum conditions on the extraction of nickel were examined. The effect of coexisting diverse ions in the aqueous phase were also examined. Less than 15 μg of nickel was quantitatively extracted into 20ml of 2.5×10^-3 M NSPS methyl isobutyl ketone solution from aqueous solution at pH 8.0-8.7, by shaking for 30 min. When a known amount of nickel was added to the artificial sea water and the sea water samples, the nickel was recovered satisfactorily. The coefficient of variation was 2.6% at 10 μg of nickel (n=6). Some samples of sea water, common salt and imported salt were analyzed.