Understanding the fundamental aspects of the surface adsorption and self-assembly of biosurfactant and biosurfactant / conventional surfactant mixtures is a major challenge for the development of bio-sustainable surfactant based products. This proposal is part of a major grant from the UK¿s dti technology programme. Glycolipid biosurfactants, such as rhamnolipids and sophorolipids, offer much potential in this area. We have now made substantial progress in understanding the adsorption of rhamnolipid / conventional surfactant mixtures. The rather different glycolipid structure and properties of the sophorolipids are expected to result in a different adsorption behaviour. We request further NR beam time on SURF / INTER to study sophorolipid / conventional surfactant mixtures