Abstract: Quantum dots (QD′s) of CdTe were prepared using L-cysteine as stabilizing agent,and the QD′s obtained at the refluxing time of 21 min (having its emission wavelength λem,at 555 nm) were used as fluorescence probe for the fluorospectrophotometric determination of hydrogen peroxide in PBS of pH 8.0 and at the excitation wavelength of 380 nm.In reaction with hydrogen peroxide,CdTe was oxidized leading to quenching of its fluorescence,and the magnitude of decrease in fluorescence intensity (ΔF) was found to keep linear relationship with concentration of hydrogen peroxide in the range from 1×10-7 to 6×10-5mol·L-1,and the value of detection limit (3s/b) was found to be 8×10-8mol·L-1.Samples of rainwater were analyzed for H2O2 contents by the proposed method and were used as matrix for testing the recovery of the method.Value of average recovery of 99.5% was obtained.