In this paper, synthesis, characterization and detection of CN^- by the compound (N^Ꞌ1E,N^Ꞌ2E)-N^Ꞌ1,N^Ꞌ2-bis((2-hydroxynaphthalen-1-yl)methylene)oxalohydrazide (1) have been reported. Compound 1 is synthesized by the reaction of oxalyldihydrazide and 2-hydroxy-1-naphthaldehyde and characterized byFTIR, ¹H NMR and ESI-Mass spectroscopy. UV–Visible spectral band of 1 is observed to be broadened and shifted to longer wavelength upon addition of CN^- ion selectively in H₂O-DMSO (8:2 v/v) medium. Based on the UV–Visible spectral data, the detection limit of cyanide ion for 1 is found to be 30.2 lM. Colourlesssolution of 1 changes to yellow in the presence of cyanide ion selectively. The same colour change is also observed on Whatman filter paper test strip. Fluorescence intensity of 1 is quenched due to the nucleophilic addition reaction of cyanide with one of the two imine carbons. ¹H NMR titration of 1 with CN^- ioncorroborates the reaction of the latter with one of the two imine carbons of the former, leading to the appearance of cyanomethyl proton signal at 6.15 ppm and consequently, its behaviour as chemodosimeter. The above mentioned chemodosimeter nature of 1 is also validated by ESI-Mass spectroscopy data. Compound 1 is capable for the detection of CN^- in water for real samples with concomitant colour change