The adsorption of pyrazole onto silver colloids has been investigated by surface-enhanced Raman scattering (SERS) experiments for normal and deuterated ligand and by ab initio density functional theory (DFT) calculations performed for surface complex models. The best agreement between observed and calculated frequencies occurs when the pyrazolide anion is bound to two partially charged Ag atoms of the colloidal surface. The formation of the adsorbate is closely related to the presence of adsorbed hydroxide anions, which are able to promote the deprotonation of the organic ligand.