The surface-enhanced Raman of 1,5-dimethylcytosine is analyzed on a metallic electrode and colloids. The obtained results reveal the existence of a chemisorption of DMC on both electrode and colloids. As a consequence, a significant contribution from the charge transfer (CT) mechanism is expected. On metal electrodes the variation of the potential induces a change of the spectral profile that can serve to evaluate the charge transfer taking place between the metal and the adsorbate. The surface-enhanced Raman scattering (SERS) spectra of DMC on the silver electrode were compared with those recorded on silver, gold, and copper colloids in order to obtain information about the electric potential existing in the colloidal surfaces as well as to estimate the importance of the charge transfer occurring in these substrates. On these metals the interaction strength tvas found to grow in the order Ag < Au < Cu, and this is related to the different energy necessary for inducing a charge transfer process between the metal and the adsorbate. Although the CT mechanism only has a weak contribution to the total SERS enhancement, in comparison to the electromagnetic, it may modify the SERS spectrum of a certain adsorbate, depending on parameters such as the surface morphology, the presence of Cl-, or the metal employed for obtaining the SERS substrate.