A composition for detecting blood includes 3 3 5 5 tetramethylbenzidine cumene hydroperoxide and a surfactant. The composition is an aqueous solution. The surfactant is an anionic surfactant or a non ionic surfactant. The composition is useful for the detection of blood in particular occult blood in saliva. Also described are methods for detecting blood using the composition a kit including the composition and the use of a surfactant to reduce the time taken to detect blood.