5,12-Naphthacenequinone (5,12-NpQ) single crystal and naphthacene (Np)-doped 5,12-NpQ mixed crystal have been prepared by crystallization from solution and characterized by X-ray diffraction analysis. Compared with the 5,12-NpQ single crystal, there is no obvious change occurring to the 5,12-NpQ/Np mixed crystal structure. The fluorescence of 5,12-NpQ/Np mixed crystals were studied and compared with that of 5,12-NpQ single crystals. It was found that the two components of the mixed crystals emit simultaneously and the fluorescence spectrum is the combination of their emission bands. No obvious energy transfer was observed in the 5,12-NpQ/Np mixed crystals, which is further supported by the data of the transient photoluminescence (PL) decays. (C) 2007 Elsevier B.V. All rights reserved.