The methyl ester sulfonate. MES, and ethyl ester sulfonate, EES, are representative of a promising group of anionic surfactants which have the potential for improved performance and biocompatibility / biosustainability. Like LAS, SLES, and MES EES undergoes a transition from monolayer to multilayer adsorption at the air-water interface in the presence of multivalent counterions. Compared to MES and SLES there are some important differences. Previous studies on MES, SLES and LAS have shown that in order to understand the detailed surface behaviour it is vital to understand the associated solution structure, and we request beam time on SANS2D to investigate the solution structure of EES in the presence of different electrolytes.