The flash point of biofuels and petroleum fuels is an essential safety-related property for fuel processing, transportation and storage. Hydroprocessed renewable diesel (HRD-76) and synthesized isoparaffin (SIP), two biofuel blend stocks, were blended with commercial petroleum aromatic fluids (aromatic 100, 150 and 200) to investigate the impacts of aromatics on biofuel flash point and to formulate blends with identical flash point characteristics as NATO F-76 marine diesel and JP-5 jet fuel. To overcome the complexity of the fuel blends, COSMO-RS ("conductor like screening model for realistic solvation") was employed to predict the flash point of these biofuel + aromatic systems. COSMO-RS calculated the flash point of alkanes and aromatics present in biofuel and petroleum fuels and the flash point of SIP + aromatics binary mixture systems. Based on the pure compound and binary mixture predictions, COSMO-RS calculations were expanded to develop surrogate mixtures for biofuels and aromatic fluids. The surrogates were in turn utilized to predict the flash point of biofuel blends with aromatics and to formulate blends with the same flash point as petroleum fuels. The COSMO-RS calculation also assisted the selection of aromatics suitable for blending with different biofuels.