The effects of nicotinamide, sodium p-toluenesulfonate and tetrapropyl and tetraburyl ammonium bromides on the cloud points of non-ionic surfactant solutions and on the solubility of an apolar dye were determined. They all revealed a continuous effect of increased solubility as the additive concentration increases. Surface tension and heats of dilution were also measured for these solutions and the results support the view of a continuous hydrotrope self-association, which is then proposed as a key process to their ability of increasing aqueous solubility of apolar compounds.