The Reversed Flow Gas Chromatography (R.F.G.C.) technique, a version of Inverse Gas Chromatography, was used to study the influence of the number of carbon atoms on the activity coefficients of the three linear alcohols methanol, ethanol and 1 propanol in their mixtures with water, in the presence of the surfactants CTAB (cationic), SDS (anionic) and TRITON X - 100 (non - ionic). The found activity coefficients, increase with increasing the alcohols' number of carbon atoms at constant temperature and pressure, as well as at constant alcohol's and surfactant's concentration and decrease with increasing the alcohol's molar fraction (at constant surfactant's concentration), as well as with increasing the number of the surfactant's films (at constant alcohol's concentration). The values of activity coefficients found for the three used alcohols, in the absence of surfactants, are in good agreement with those calculated theoretically or found in the literature. The precision of the Reversed - Flow Gas Chromatography for measuring activity coefficients of alcohols is approximately high (94.12% for methanol, 99.26% for ethanol and 94.35% for 1-propanol), showing that R.F.G.C. is a precise method not only for measuring activity coefficients of alcohols, but also for studying the influence of various parameters (molecular formula of linear alcohol, type of surfactant, as well as alcohol's and surfactant's concentration) on the measured activity coefficients. (C) 2019 Elsevier B.V. All rights reserved.