Dichloro 1,3,5 triazinoxy)quinoline (DTQ) was evaluated as a new fluorescent reagent for determining hydrogen peroxide. It was found that the fluorescence intensity of DTQ in alkaline medium could be dramatically enhanced upon addition of H 2O 2. Based on this effect, a simple and selective method for the spectrofluorimetric determination of hydrogen peroxide was established. The relative standard deviation of the method was found to be 1 1% for 9 replicate determinations of a 4 6×10 -6 mol/L hydrogen peroxide solution. The linear range was 2 3×10 -7 -2 3×10 -5 mol/L with a detection limit of 2 2×10 -8 mol/L ( S/N =3). The method was attempted to determine hydrogen peroxide in synthetic human serum samples with satisfactory results. Dichloro 1,3,5 triazinoxy) quinoline (DTQ) was evaluated as a new fluorescent reagent for determining hydrogen peroxide. It was found that the fluorescence intensity of DTQ in alkaline medium could be dramatically enhanced upon addition of H 2O 2. Based on this The relative standard deviation of the method was found to be 1 1% for 9 replicate determinations of a 4 × 10 -6 mol / L hydrogen peroxide solution. The linear range was 2 3 × 10 -7 -2 3 × 10 -5 mol / L with a detection limit of 2 × 10 -8 mol / L (S / N = 3). The method was attempted to determine hydrogen peroxide in synthetic human serum samples with satisfactory results.