Rhamnolipids (RhLs) are biosurfactants that are highly surface active. Recent work by Liley elucidated interesting behaviour between C12E8, a common non-ionic surfactant, and RhLs: the RhLs suppress temperature effects on the non-ionic between 10 and 30˚C. This suggests a larger change in the free energy of mixing between the two species. The proposed experiment aims to understand the interplay of co-adsorption between RhLs and non-ionic surfactants over a range of pH values and temperatures. Neutron Reflectivity, coupled with isotopic substitution, allows adsorption of the individual components within the binary systems to be determined experimentally. These results will be compared to theoretical predictions based on the pseudophase model. The neutron data will allow an accurate calculation of the free energy of mixing for the system and help understand RhL behaviour.