This study is concerned with the development of a thermodynamic model that can be used for numerical simulations of mixtures of fluids, whereby some of the mixture components cannot be accurately modeled by a thermally perfect equation of state. Upwind-type algorithms for the discretization of the inviscid fluxes are introduced in some detail, including preconditioning for low-speed problems. Results are obtained for a challenging test case involving the combustion of a liquid oxygen/gaseous hydrogen mixture at high pressure, and they compare reasonably well with experimental data. © 2007 Elsevier Ltd. All rights reserved.