AbstractData on azeotropic mixtures published in the literature often show large scattering. In this study two experimental methods are developed for determination of these data: one method is based on determination of the position of the minimum in the boiling point curve; the other method is based on distillation by means of a very efficient column. Both methods are applied to the systems formed by the representatives of the homologous series of alkanes from pentane to nonane branched hydrocarbons also included and of the homologous series of alcohols from ethanol to pentanol. The results obtained by both methods are in good mutual agreement. This increases the reliability of the data. The data are also computed by means of a method based on the group contribution method. Agreement of computed and experimental data is satisfactory.