The　calculated　values　of　transport　properties　of　mixtures　of　carbon　and　argon,　and　carbon　and　helium,　at　high　temperatures　are　presented　in　this　paper.　The　transport　properties　are　evaluated　by　using　the　Chapman-Enskog　method　expanded　up　to　the　third-order　approximation　(second-order　for　viscosity).　Collision　integrals　were　obtained　using　the　most　accurate　cross-section　data　that　could　be　located.　The　results　are　compared　with　those　of　previously-published　studies.　Good　agreement　is　found　for　pure　argon　and　helium.　Larger　discrepancies　occur　for　mixtures　of　carbon　and　argon,　and　carbon　and　helium;　these　are　explained　in　terms　of　the　different　values　of　the　collision　integrals　that　were　used.　The　results　presented　here　are　expected　to　be　more　accurate　because　of　the　improved　collision　integrals　employed.