This article examines the problems of determining and comparing mutual diffusion coefficients of binary gas mixtures in the temperature range of 273–373 K at atmospheric pressure. The characteristic features of experimental data presented in the classical compilation by Marrero & Mason are analyzed and compared with calculated values obtained using the semi-empirical Fuller method and the kinetic-theoretical Chapman–Enskog method. The necessity of refining the temperature dependences of diffusion coefficients for systems involving hydrocarbon and non-hydrocarbon gases used in oil and gas and energy processes is substantiated. Based on the analysis, the author shows that the applied models reflect experimental trends to varying degrees: the Chapman–Enskog method better describes light gas mixtures, whereas the Fuller correlation provides satisfactory agreement for heavier hydrocarbons. Conclusions are drawn regarding the applicability ranges of each approach, and the practical significance of the results for mass transfer calculations in engineering models and numerical simulations of diffusion processes is highlighted.