A phosphorus-containing flame retardant, bisphenol S-bis (5,5-dimethyl-1,3-dioxaphosphorinanyl-2oxy phosphate ester) (BSDOPE), was synthesized and characterized by elemental analysis (EA), mass spectra (MS), infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). The thermal stability of BSDOPE was investigated by thermogravimetric analysis (TGA). The solubilities of flame retardant BSDOPE in selected solvents are measured. Several thermodynamic models, including the ideal, modified Apelblat, Wilson, NRTL, UNIQUAC, the combined Nearly Ideal Binary Solvent (NIBS)/Redlich-Kister, and Scatchard-Hildebrand models, were applied to correlate the experimental solubility data. The results show that the calculated values indicated good agreement with the experimental data. (C) 2014 Elsevier B.V. All rights reserved.