Quantitative structure-property relationships (QSPRs) are increasingly used for the prediction of physicochemical properties of pure compounds, but only a few have been developed to predict the properties of mixtures. In this work, a series of existing and new formulas were proposed to derive mixture descriptors for the development of QSPR models for mixtures. These mixture descriptors were used to model the flash points of a series of 435 organic mixture compositions. Multilinear models were obtained using 12 different mathematical formulas, taking into account the linear or nonlinear dependence of the flash point on the concentration of each compound. The best model, issued from the newly proposed (x(1)d(1) + x(2)d(2))(2) formula, was a four-parameter model presenting good prediction capabilities (with a mean absolute error in prediction of 10.3 degrees C) compared with existing predictive methods for both mixtures and pure compounds.