Report describing a study regarding the solubility and related properties of tributyl phosphate (TBP), which has lower solubility in water than most uranium solvents. Pure TBP and TBP in an inert diluent were tested for solubility in water, several nitric acid solutions of varying concentrations, and other solutions typical of process streams. For TBP-diluent-water system tests, equilibrium water content in organic phase was found.