The T-1 <-- S-0 absorption spectrum of 4H-pyran-4-thione (PT) was measured in a static cell at room temperature (550-620 nm) and in a seeded cold supersonic jet (580-600 nm) using the cavity ring-down (CRD) method. In the static cell absolute extinction coefficients were determined between 573 and 610 nm with an accuracy of &SIM;+/-5%. In this region 22 harmonic sequences and 18 hotbands were observed. The energetically lowest ground state vibration at 167.5 cm(-1) was identified as the promoting mode in the static PT gas. The mode in the triplet state was found at 152.3 cm(-1). The CRD absorption spectra of static PT gas and jet-cooled PT are compared with the phosphorescence excitation spectrum of isolated PT. The weak S-1.0 <-- S-0.0 absorption was tentatively assigned to a transition at similar to 17433 cm(-1). (C) 2002 Elsevier Science (USA).The T-1 <-- S-0 absorption spectrum of 4H-pyran-4-thione (PT) was measured in a static cell at room temperature (550-620 nm) and in a seeded cold supersonic jet (580-600 nm) using the cavity ring-down (CRD) method. In the static cell absolute extinction coefficients were determined between 573 and 610 nm with an accuracy of &SIM;+/-5%. In this region 22 harmonic sequences and 18 hotbands were observed. The energetically lowest ground state vibration at 167.5 cm(-1) was identified as the promoting mode in the static PT gas. The mode in the triplet state was found at 152.3 cm(-1). The CRD absorption spectra of static PT gas and jet-cooled PT are compared with the phosphorescence excitation spectrum of isolated PT. The weak S-1.0 <-- S-0.0 absorption was tentatively assigned to a transition at similar to 17433 cm(-1). (C) 2002 Elsevier Science (USA).