Photothermal calorimetry and fluorescence spectroscopy were used to determine the relaxations of the photoexcited singlet state of two PPV and polyfluorene oligomers, (E,E)-1,4-bis [(2-benzyloxy)styryl] benzene (PVDOP) and ter(9,9 '-spirobifluorene) (TSBF). The decay rates of different S, relaxation channels, which include intersystem crossing (ISC), radiative, and nonradiative decay can be determined by the combination of photoacoustic calorimetry (PAC) and the time-correlated single photon counting (TCSPC) technique. The triplet state energy level is determined by the phosphorescence (Ph) spectra recorded at 77 K. The ISC yields are similar to 3% and 6% for PVDOP and TSBF, respectively. The T-1 to S-0 transition decay rate is acquired by PAC and photothermal beam deflection (PBD) measurements. The triplet state decay rate is 17 and 21 ms(-1) at room temperature. The Ph intensity decay at 77 K shows that the triplet state lifetime increases by 4 orders of magnitude, as compared to room temperature.