3-Cyano-4-methylcoumarin is a 3-substituted 4-methylcoumarin derivative. Its structural properties, vibrational frequencies and electronic spectra has been studied by density functional theory (DFT). It has been reported to be formed during the Knoevenagel condensation of o-hydroxyacetophenone with ethyl cyanoacetate catalyzed by calcined Mg-Al hydrotalcite. Synthesis of 3-cyano-4-methylcoumarin, via condensation of o-hydroxyacetophenone with ethyl cyanoacetate in the presence of sodium ethylate, has been reported.