The interface of CaCO3 (calcite) and water or oil is of paramount importance in a number of key academic and industrial areas, not least oil recovery and scale deposition in domestic and industrial situations. Neutron reflection has proved to be an outstanding approach for the study of solid/liquid interfaces and in this proposal we plan to exploit the power of this technique to investigate the adsorption of the particularly important anionic surfactant aerosol-OT (AOT, sodium di-2-ethylhexylsulfosuccinate)at the calcite/oil interface.