Abstract Sensitized fluorescence and fluorescence quenching has been studied in pyrene layers, doped with small amounts of coronene, anthraquinone and acenaphthylene. Coronene exhibits strong sensitized fluorescence at room temperature, but not at 77°K. This behaviour is due to decreased exciton mobility. The activation energy of the excition hopping process has been determined to be Ea = 0.055 eV. The lifetime of pyrene excimer fluorescence is decreased by quenchers in accordance with the steady-state measurements of relative quantum efficiencies. Three possible mechanisms of excimer state hopping in jpyrene are discussed