To investigate the microscopic solvation effect on the intramolecular charge-transfer (ICT) reaction of (p-cyanophenyl)pentamethyldisilane (CPDS), laser-induced fluorescence and dispersed fluorescence (DF) spectra of clusters of CPDS solvated by H2O or acetonitrile (AN) were observed in supersonic jets. In both clusters, a dual emission originating from a locally excited (LE) pipi* and a charge-transfer (CT) state was observed. Two significant microscopic solvation effects were observed: an increase in the Stokes shift and an acceleration of the ICT process. The increases in the Stokes shift were found to be 1100 and 1700 cm(-1) for CPDS-(H2O)(1) and -(AN)(1), respectively. A trend of these clusters was related to the stabilization of the CT state by the dipole-dipole interaction with the solvent molecule. Concerning the rate of the ICT process, an unexpected result was found by lifetime measurements. The rate of the ICT process is found to be slower in the case of the CPDS-(AN)(1) cluster than that of the CPDS-(H2O)(1) cluster, while the stabilization of the CT state is larger in the former. It was considered that this behavior reflects a reduction of a Franck-Condon overlap between the LE and the CT states, which comes from changes in the relative orientations between the LE and the CT states in the cases of these clusters.