AbstractNew, absolute measurements of the thermal conductivity of liquid n‐hexane and n‐octane are reported. The measurements have been carried out within the temperature range 34—90°C and over the pressure range 1.8 — 640 MPa in a transient hot‐wire instrument. It is estimated that the experimental data have an uncertainty of ±0.3%. The density dependence of the thermal conductivity of n‐hexane and n‐octane may be satisfactorily represented by means of an equation whose form is based upon an heuristic modification of the Enskog theory for transport processes in dense fluids. The optimum correlations for n‐hexane and n‐octane are slightly different from those which have been found to be universal among normal alkanes with an odd number of carbon atoms. This behaviour is predominantly attributable to the superior accuracy of the present experimental data, resulting from an improved treatment of radiative heat transport