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From measurements of the phosphorescence spectrum and its decay at 77 K, the lowest triplet state of benzophenone (BP) at low concentrations (ca. 1 x mol dm-3) has been assigned to be of nn* character even in a strong hydrogen-bonding solvent such as 2,2,2-trifluoroethanol (TFE). At high sample concentrations (ca. 1 x mol dm-3), another nn*-type phosphorescence due to aggregated BP is observed. Addition of water (H,O or D,O, 1-4 vol.%) to BP-TFE solutions causes dual phosphorescence with lifetimes of 3.6 and 15.9 ms, but only the long-lived phosphorescence is observed in TFE-water (a5 vol.%): The nn*-type short-lived phosphorescences at low and high sample concentrations are attributed to free triplet BP (or BP hydrogen-bonded with TFE) and aggregated triplet BP, respectively, while the long-lived phosphorescence is attributed to a complex of triplet BP-water-TFE (1 : 1 : 1) or triplet BP-water (1 : 1) of mixed nn*-nn* character.