Pyrromethene dyes, particularly PM 567, have been studied in liquid media using various spectroscopic techniques. Photodecomposition of dyes was monitored by absorption and fluorescence spectroscopy. In laser flash photolysis experiments on dyes in liquids, phototransients were observed (microsecond time domain) that included dye triplets and at least one other transient of the radical or radical-ion type. Experiments included product studies that allowed identification of major products of photodegradation; an assessment of the effectiveness of known stabilizing additives such as DABCO and butazate was also conducted. Purposes of the work included definition of the roles of energy and electron transfer mechanisms in dye photodegradation and the effects of oxygen or additives in dye media.