Hydrogen bonding effects on reorganization energies (lambda) in the photoinduced electron donor-acceptor system of duroquinone (DQ)-1,2,4-trimethoxybenzene (TMB) in benzonitrile have been investigated by time-resolved EPR and cyclic voltammetry measurements. The solvent reorganization energies (lambda(S)) determined for the radical ion pair systems involving the hydrogen-bonded complexes are larger by similar to0.2 eV than those calculated from the Marcus continuum dielectric model. The present results suggest that dissociation of the DQ anion-alcohol hydrogen-bonded complex results in the new component of As for the charge recombination reaction in polar solvents. (C) 2003 Elsevier Science B.V. All rights reserved.