Original scientific paper https://doi.org/10.2298/TSCI140815045RIn this study, a theoretical model of film condensation inside horizontal tubes with more precise definition of friction coefficient on interphase is presented to calculate the heat transfer coefficient under two-phase annular and intermediate flow conditions. This more precise definition contains experimental substantiation of correction for calculation of pressure losses by friction and correction that takes into account surface suction on the interphase. Comparison of this model with the experimental data of various authors demonstrates that the results are in satisfactory and close agreement.