The application of in situ surface enhanced Raman scattering (SERS) spectroscopy to aspects of mineral processing is discussed. In the study of flotation systems, SERS has been used to characterise the species formed on coinage metal surfaces over a range of controlled potentials for ethyl, i-propyl, i-butyl and i-amyl xanthates, for O-isopropyl-N-ethylthionocarbamate (IPETC), for 2-mercaptobenzothiazole (MBT), and for diisobutyl dithiophosphinate (DIBDTPI). For each collector, adsorption occurs via charge transfer to form a metal-sulfur bond and, in situations in which the reversible potential for the formation of the bulk phase is known, at underpotentials. The dissolution of silver in basic solutions containing cyanide has been shown to be inhibited by MBT and by DIBDTPI as a result of the chemisorption of the collector species. In hydrometallurgy, SERS has been applied to the investigation of gold leaching. Changes in the surface species that occur during gold cyanidisation as the potential is varied have been identified from SERS spectra recorded in real time on voltammograms. In electrometallurgy, SERS investigations of copper electrodeposition from sulfuric acid solutions have shown that a transient surface sulfate species is involved in the plating process.