Colloidal solutions of ferric oxide nanoparticles of different particle size and surface area characteristics enhance the intensity of the chemiluminescent (CL) reaction of luminol with hydrogen peroxide up to 18-fold and accelerate the rate of the reaction time to 86-fold. The sample with the highest enhancement was applied in the determination of hydrogen peroxide and the estimation of hydrogen peroxide scavenging activity of selected antioxidant compounds. Hydrogen peroxide was determined down to 1.25 x 10(-3) M (S/N = 3). Regarding the hydrogen peroxide scavenging activities of the selected organic antioxidants it. was found that mono- and dihydroxylated phenols (tyrosol, catechin and caffeic acid) exhibit up to one order of magnitude higher scavenging activity than trihydroxylated phenols (gallic acid and pyrrogallic acid), vitamins E and C, and amino acid cysteine. (c) 2008 Elsevier B.V. All rights reserved.