A series of two layer InAsSb films were grown with molecular beam epitaxy (MBE). We report the effect of substrate temperature on the composition of InAsSb grown with and without a Bi surfactant and find that the Sb incorporation is suppressed as the substrate temperature increases, and that it is also further suppressed by the presence of Bi at all temperatures. We examine the data with a kinetic model, which gives insights into the composition of mixed anion alloys using straightforward rate equations for each process that occurs during growth. It was shown that the reduction in Sb composition is due to the preferential removal of Bi by As, and that removal rate obeys an Arrhenius dependence with an activation energy of 1.35 eV. Published by Elsevier B.V.