In aprotic organic non-aromatic solvents, dibenzoylmethanatoboron difluoride (DBMBF 2) shows in addition to the monomeric fluorescence peaks, a broad fluorescence band at 522 nm in the concentration region [DBMBF 2] > 1 × 10 −2 M; the broad emission is ascribed to a DBMBF 2 excimer which is formed by a dynamic process. In the [DBMBF 2] = 10 −7 to 10 −3 M region, DBMBF 2 shows two fluorescence peaks at 398 and 416 nm; the latter peak becomes stronger at the expense of the former at higher concentrations and is the only emission peak at 10 −3 M. The two fluorescence peaks are ascribed to two conformers of DBMBF 2 in solution. DBMBF 2 forms a stable ground state complex with benzene, but relatively unstable complexes with electron-rich olefins, dienes and tertiary amines. In contrast with the strong exciplex fluorescence emission in the presence of benzene, DBMBF 2 fluorescence is quenched by trans-anethole and tertiary amines with no new emission.