Recent studies have identified uncertainties in fuel diffusion coefficients as a source of significant uncertainty in combustion modeling. This paper presents accurate binary diffusion coefficients of linear hydrocarbons in helium and nitrogen at temperatures from 300 K to 723 K. Diffusion coefficients are determined using a reversed-flow gas chromatography (RF-GC) system. Earlier work in our laboratory has established the validity of this methodology for noble gases and methane under these elevated-temperature conditions, and we utilize the methodology to measure diffusion coefficients for longer chain systems of interest in combustion modeling: ethane, propane, and n-butane. For propane and n-butane in nitrogen, the present results show dramatically different (up to 16.9% deviation at the highest common temperature) diffusion coefficients than previous work in addition to extending the available temperature range. The effects of decomposition of the analyte at higher temperatures and adhesion of the analyte on the diffusion column at lower temperatures during the measurements are briefly considered but have only a small impact on the present systems. Published by Elsevier Inc. on behalf of The Combustion Institute.