A heterogeneous reaction-based colorimetric chemodosimeter toward cyanide anions was designed based on a hybrid pyrylium/alumina probe which possesses a great selectivity for CN(-) over other common anions even at significantly higher concentrations. The synergistic incorporation of the inorganic matrix and the organic receptor can play a pivotal role in the convenient field-usable determination of this toxic anion in water. Moreover, the catalytic properties coming from the inorganic matrix can greatly amplify the sensor performance.