By using the previously developed roughening method for producing SERS-active Rh electrode, and assistedby the highly sensitive confocal microprobe Raman system, we carried out a detailed SERS study on thedissociation and electrooxidation of C1 molecules on a Rh surface. The SERS spectra obtained in a widefrequency region provide not only the vibrations reflecting the internal bonding of CO (at ca. 2000cm-1) butalso the bonding between CO or O with Rh (at ca. 450cm-1). A complementary electrochemical study wasalso performed on the roughened Rh surface in order to correlate the electrochemical and vibrationalinformation. Both electrochemical and SERS studies show that Rh has no discernible activity toward theelectrooxidation or dissociation of methanol in acidic solutions. Rh becomes active and its activity increaseswith the decrease of the solution acidity. For HCHO and HCOOH, the electrooxidation activity of Rh increaseswith increasing pH. On the basis of the result of the model CO system, discussion on the dissociation orelectrooxidation mechanisms was presented for C1 molecules on Rh.