The aim is to investigate and understand interactions of hydrotropes (primitive amphiphiles) with a new range of industrially important non-ionic surfactants, alkyl-capped polyalkylethoxylate ethers. This will help improve understanding of mixed hydrotrope-surfactant interactions, about which only very little is known. The compounds of study are shown in Figure 1 being a matrix of three hydrotropes (cationic, anionic, and non-ionic) and four structurally related non-ionic surfactants. This systematic approach will not only reveal the dominant effects of hydrotrope class on micellar aggregation, but also the influence of headgroup hydrophobicity, a factor which is becoming increasingly important in industrial applications. This PhD project (student AN) is partly sponsored by Syngenta, and the results will help to improve the performance and efficiency of agrochemical formulations.