Cyanide is well known one of the most toxic materials and extremely harmful to the environment and human health.[1] Its concentration in drinking water is limited to less than 2 μM according to the World Health Organization.[2] We prepared a coumarin-barbituric acid conjugate (Scheme 1),where the coumarin moiety was designed to function as a signaling unit,the conjugated unit as a reaction unit,and the barbituric acid as an activation unit.