We developed a novel boradiazaindacene derivative to detect cyanide ions in solution at micromolar concentrations. This structurally simplechemosensor displays a large decrease in emission intensity and a reversible color change from red to blue on contact with cyanide ions.Highly fluorescent polymeric films can be obtained by doping with the chemosensor. Such polymeric materials can be used for the sensingof the cyanide ions in polymer matrices.