A kinetic fluorimetric method is described for the first time for the determination of microamounts of nickel (II) which is based on the catalytic effect of this ion on the oxidation of pyridoxal hydrazone by potassium peroxidisulphate. The reaction is followed by measuring the rate of change in the fluorescence of the oxidation product (λex315, λem370 nm). The calibration graph is linear in the 50–300 ng Ni mL−1range. The analytical properties of the reagent are also described and the kinetic parameters of the reaction are reported.