The excited singlet state properties of 4'-nitro- and 2',4'-dinitro-substituted trans-4-hydroxystilbenes were studied in various solvents. The fluorescence quantum yield (Phi(f)) of the former compound in solvents unable to form strong hydrogen bonds goes through a maximum as a function of the solvent polarity parameter E-T(N), reaching the highest value of 0.31 in butyronitrile. In contrast, a monotonous diminution of Phi(f) and moderate changes were found in hydrogen bonding media. The addition of nitrogen-heterocyclic compounds leads to both dynamic and static fluorescence quenching due to excited-state proton transfer along the hydrogen bond. trans-2',4'-Dinitro-4-hydroxystilbene emits only weak fluorescence in all solvents studied. (C) 2010 Elsevier B.V. All rights reserved.