Abstract: Means and method for the detection of hydrogen peroxide or of hydrogen peroxide-forming substrates, consisting of 4-aminoantipyrine and an aromatic amine or phenol and a neutral to weakly acid buffer as well as other additives and reagents which form H.sub.2 O.sub.2 with the substrate and which are known for use in Trinder's reaction, the 4-aminoantipyrine, in the immiscible state before use, being separate from the acid buffer and from the other reagents if any, and being mixed with a small amount of an alkaline buffer having a pH of 8.5 to 14.0, the two compositions being combined, in a quantity ratio to one another that is suitable for the detection test, in a single package or in a single-use unit.