Tetrahydrocurcumin (THC), a cosmeceutical is one of the major metabolite and reduced form of curcumin. Simple, sensitive, selective, rapid and reliable method for the spectrophotometric determination of tetraydrocurcumin has been developed. The method is based on the reaction of THC with iron (III) and subsequent reaction with ferricyanide to yield a Prussian Blue product with a maximum absorption at 720 nm. The method obeys Beer's law. As many as ten each of anions and cations listed do not interfere.