The relative influences of the reorganization energies of the classical and quantum modes on the maximum position of the rate constant – reaction free energy curve have been studied. In the framework of the continuum electrostatics, the electron transfer reorganization energies in methyltetrahydrofurane solutions for the system biphenylyl – spacer – acceptor were calculated. For different acceptors the solvent reorganization energy varies from 1.0 to 1.1 eV. When added with the rather small reorganization energies for classical intra-molecular modes we obtain 1.13 - 1.34 eV. With account of possible errors this coincides practically with the experimental estimate of the energy at the maximum of the rate–free energy curve DGmax ? -1.2 eV. Hence, we can conclude that the reorganization of quantum modes does not influence substantially the position of this maximum. To the contrary, in a non-polar solvent isooctane were the solvent reorganization does not play any role the reorganization of the quantum intra-reactants modes becomes determinant. These conclusions agree fully with the results of the general theoretical analysis and should be accounted for in the experimental data interpretation.