Au nanoparticles (AuNPs) are good quenchers once they closely contact with luminophore Here we reported a simple approach to obtain enhanced electrogenerated chemiluminescence (ECL) behavior based on Au/CdS nanocomposite films by adjusting the amount of AuNPs in the nanocomposite The maximum enhancement factor of about 4 was obtained at an indium tin oxide (ITO) electrode in the presence of co-reactant H2O2 The mechanism of this enhancement was discussed in detail The strong ECL emission from Au/CdS nanocomposites film was exploited to determine H2O2 The resulting ECL biosensors showed a linear response to the concentration of H2O2 ranging from 1 0 x 10(-8) to 6 6 x 10(-4) mol L-1 with a detection limit of 5 nmol L-1 (S/N = 3) and good stability and reproducibility (C) 2010 Elsevier Ltd All rights reserved