Surface-enhanced Raman scattering (SERS) spectra of tetramethylammonium ions ((CH3N+) adsorbed on silver electrodes are reported and compared to the normal Raman spectra (NRS) from solutions. Shifts in Raman frequencies for most modes of the (CH3N+ ion have been observed. The SERS spectra are strongly dependent on the applied potential. Halide ions appear to mediate the adsorption of the (CH3N+ cations at the positive electrode surfaces, and the electromagnetic enhancement mechanism is largely responsible for SERS. Decomposition of (CH3N+ occurs at the silver electrode surfaces when the potential becomes sufficiently negative. It is suggested that a hydrocarbon is the major decomposition product adsorbed on the silver surfaces; although trimethylamine is a possible product, evidence suggests that only a small amount of this substance is on the surface.