Nowadays, hydrogen peroxide (H(2)O(2)) has attracted more and more attentions in biochemical fields owing to its important role in biological systems. In this contribution, we propose a novel assay for the detection of H(2)O(2) based on the cleavage of ssDNA on gold nanoparticles (AuNPs). It was known that AuNPs could be stable in the presence of single-stranded DNA (ssDNA) which prevents the salt-induced aggregation of AuNPs in solution owing to the electrostatic repulsion. However, hydroxyl radical (HO*) generated from Fenton reaction could cleave the ssDNA and induce the aggregation of AuNPs. Therefore, color change from red to blue owing to the plasmon resonance absorption (PRA) of AuNPs can be observed by the naked eyes and enhancement of plasmon resonance light scattering could be measured with a common spectrofluorometer. The values of A(650)/A(520) of the PRA band were found to be linearly proportional to the concentration of H(2)O(2) in the range of 2.0 x 10(-7) to 8.0 x 10(-6) mol L(-1) with the limit of determination (LOD) being 40 nmol L(-1) (S/N=3), and thus the content of H(2)O(2) in rat encephalon extraction could be successfully detected with the recovery in the range of 98-103%.