Triphenylphosphine oxide (TPPO) was characterized by a differential scanning calorimeter (DSC) and nuclear magnetic resonance ((1)H NMR and IT NMR). Using a static analytical method, the solubilities of TPPO were measured in benzene, toluene, ethyl acetate, and binary solvent mixtures: benzene + ethyl acetate (volume fraction = 0.5); toluene + ethyl acetate (volume fraction = 0.5); toluene + benzene (volume fraction = 0.5). The experimental results were correlated with an empirical equation. The estimated uncertainty of all the solubility values was within 2.0 %.