Composition for the detection of(a) hydrogen peroxide or hydrogen peroxide forming substrates or(b) peroxidases or peroxidatively reacting substances which composition comprises a substrate capable of coupling and an oxidizable substance known to undergo the Trinder reaction, and(a) a peroxidase or(b) hydrogen peroxidewherein the substrate capable of coupling is a compound of the formula ##STR1## in which n and m are individually selected from whole numbers of 1 to 4,X and Y, which can be the same or different represent a valence bond or a phenylene radical,R.sub.1 and R.sub.2 are individually selected from carboxyl or sulfonic acid groups and one of R.sub.1 and R.sub.2 can also be hydrogen or lower alkyl, andR.sub.3 and R.sub.4 are individually selected from hydrogen and alkyl radicals of up to 6 carbon atoms;and/or a salt of such compound.The present invention also provides a method wherein the composition is brought together with a sample and the coloration obtained is evaluated visually or with a photometer.