Vibrationally resolved electronic spectra of jet-cooled cis and trans isomers of 1-methyl-2-phenylcyclopropane (cis-MPCP and trans-MPCP) were recorded using resonant two-photon ionization. Each isomer was found in a single conformation. Spectroscopic evidence reveals that in the trans isomer the plane of the phenyl ring bisects the 60 degrees internal bond angle of the cyclopropyl ring in both the ground and excited electronic states. Extensive Franck-Condon activity in the low-frequency phenyl torsion mode is observed in the spectrum of cis-MPCP, suggesting that a substantial change in torsional geometry is induced by electronic excitation. Excited state CIS calculations predict that the phenyl ring rotates over 20 degrees toward a bisected conformation in the excited state. (C) 2012 Elsevier B. V. All rights reserved.