A spectroelectrochemical ATR cell has been constructed for in-situ FTIR measurements of ethyl xanthate adsorption on chalcocite, chalcopyrite, pyrite and galena at pH 9.2. It allows potential control while conditioning the mineral bed electrode and subsequently recording the spectra. The results obtained with chalcocite identify three different potential regions of xanthate adsorption, including chemisorption, copper ethyl xanthate formation on the surface and multilayer formation. On chalcopyrite, xanthate initially forms dixanthogen, followed by copper ethyl xanthate at higher potentials. Dixanthogen is the only surface species identified on the surface of pyrite. Lead ethyl xanthate-like species are formed on the surface of galena at potentials where the voltammogram shows a pre-wave for chemisorption.