Surface-enhanced Raman scattering (SERS) was employed to investigate the adsorption of thiourea (TU) on the silver electrode at different applied electrode potentials. The SER intensities were interpreted by an algorithm originally proposed by Wu et al. [J. Chem. Phys. 87 (1987) 7300] to elucidate the bond polarizability derivatives. The results showed that TU is adsorbed on the electrode via the S atom with a tilted orientation. An extended Huckel molecular orbital (EHMO) calculation was employed to explain the charge transfer between TU and the silver electrode surface.