In this study, electrochemically roughened gold is modified with underpotential deposition (UPD) silver to investigate the effects on enhancements in the intensity and the thermal stability of surface-enhanced Raman scattering (SERS). The SERS of Rhodamine 6G (R6G) adsorbed on the UPD Ag-modified Au substrate exhibits a higher intensity by six-fold of magnitude, as compared with that of R6G adsorbedon the unmodified Au substrate. Moreover, the SERS enhancement capabilities of UPD Ag-modified Au and unmodified Au substrates are seriously depressed at temperatures higher than 200 and 150 • C, respectively. It indicates that the modification of UPD Ag can significantly depress the thermal destruction of SERS-active substrates.