In this work, activity coefficients at infinite dilution (gamma(infinity)(13)) have been measured for 21 solutes (subscript 1) (alkanes, cycloalkanes, alkenes, aromatic compounds, alcohols, esters, ketones, and halogenated hydrocarbons), in four solvents (subscript 3), namely one saturated fatty acid and three unsaturated fatty acids: stearic (octadecanoic) acid - C18:0, oleic (cis-9-octadecenoic) acid -C18:1 9c, linoleic (cis, cis-9,12-octadecadienoic) acid - C18:2 9c12c, and linolenic (cis, cis, cis-9,12,15-octadecatrienoic) acid - C18:3 9c12c15c, by gas-liquid chromatography. The measurements were carried out at temperatures from (303.13 to 368.19) K and the partial molar excess Gibbs free energy (Delta G(1)(E,infinity)), enthalpy (Delta H-1(E,infinity)), and entropy (Delta S-1(E,infinity)), at infinite dilution were calculated from experimental gamma(infinity)(13) values obtained over the temperature range. The uncertainties in determination of gamma(infinity)(13) and Delta H-1(E,infinity) are 4% and 20%, respectively. The results for stearic acid obtained in this study have been compared to those available in the Dortmund Data Bank (DDB). The real behaviour of fatty systems could be better understood through the results obtained in this work. (C) 2013 Published by Elsevier Ltd.