The lowest excited triplet (TO state of the most widely used UV-B absorber, octyl methoxycinnamate (OMC), has been studied through measurements of phosphorescence and electron paramagnetic resonance spectra in rigid solutions at 77 K. The energy level and lifetime of the T-1 state of OMC were determined. The observed T-1 lifetime and zero-field splitting parameter suggest that OMC possesses mainly a (3)pi pi* character in the T-1 state.