We study the behavior of the reorganization energy for simple charge transfer reactions in mixtures of dipolar hard sphere fluids by Monte Carlo simulation. The static dielectric constants of the solvents are also obtained from the simulation. They are used as input in the reorganization energy expressions provided by the Marcus theory and the mean spherical approximation. Thus, a comparison between the values obtained from the theoretical expressions and our simulation results is possible. The dependence of the reorganization energy with the mixture composition and the influence of preferential solvation effects is also discussed.