The pressure dependence of the self‐diffusion coefficients of several normal paraffin hydrocarbons and the isomers of hexane have been determined. In addition, the temperature dependence of self‐diffusion coefficients has been measured for the isomers of hexane. Energies and volumes of activation have been calculated. With the exception of 2, 2‐dimethyl butane, these parameters do not change significantly with branching in the isomers of hexane. The volumes of activation are about 10–20% of the molar volumes in all cases. Diffusion coefficients computed from a semiempirical modification of an equation derived by Longuet‐Higgins and Pople are compared with the experimental results.