Surface enhanced Raman scattering (SERS) spectroscopy at surfaces under electrochemical control has been applied to elucidate the adsorption of thiol collectors. SERS spectroelectrochemical studies at coinage metal electrodes have been carried out on ethyl xanthate, and three isoxanthates, O-isopropyl-N-ethylthionocarbamate, 2-mercaptobenzothiazole, diisobutyldithiophosphinate and butylethoxycarbonylthiourea. For each collector, adsorption occurs via charge transfer to form a metal-sulfur bond and, in situations for which the reversible potential of the formation of the bulk phase is known, at underpotentials. Mercaptobenzothioazole was detected on chalcopyrite after immersion in a solution of the collector after the deposition of gold to induce SERS. (C) 2005 Elsevier Ltd. All rights reserved.