Infrared carbonyl and carbon-carbon double bond frequencies in appropriate solution, solid state and nujol are presented for a number of substituted 2H-pyran-2~nes. The effect of- the substituents at the 3-,4- and 4,6-positions on the carbonyl absorption frequencies of the 2H-pyran-2­one has been interpret~d in te~s of chemical effects. The influence of the amino group at the 3­position, p-methoxy phenyl at 4 or 4,6-positios and hydroxystyryl at the 6-position of the 2-H­pyran-2~De has been found to lower the carbonyl absorption significantly as compared to the general­ly reported value of 1700 em-I OJ; above 1700 em-I.