Activity coefficients at,infinite dilution provide a useful tool for solvent selection in extractive distillation or extraction processes. in this work activity coefficients at infinite dilution for various solutes (alkanes, cycloalkanes, alcohols, aromatic hydrocarbons, xylenes and alkenes) in the solvent 1-octanol were measured at four temperatures, (293.44, 303.45, 313.55, and 323.43) K, with the help of gas-liquid chromatography. The adsorption at the gas-liquid interface between the solutes and the solvent was examined by varying the solvent liquid loading in the columns, Corrected retention values taking adsorption effects into account are determined and are used to calculate the activity coefficients at infinite dilution. These values compare well with various activity coefficients taken from the literature using different techniques and the predicted values using the modified UNIFAC (Dortmund) method. An important application of the present data can be seen in the use of 1-octanol as a solvent for processes such as extractive distillation or extraction. It is sufficient to know the separation factor at infinite dilution of the components to be separated in order to determine the applicability of 1-octanol as a selective solvent.