Due　to　the　application　of　thermal　barrier　coatings,　the　concentrations　of　Cr　in　turbine　blade　alloys　have　been　limited　to　low　values　(approximately　5　at.%　or　less)　since　the　introduction　of　second-generation　single-crystal　superalloys.　Thermal　oxidation-induced　rumpling　and　swelling　of　coating　could　lead　to　coating　spallation　and　inner　alloy　failure,　especially　in　advanced　thin-wall　turbine　blades.　The　initial　oxidized　surface　morphologies　and　elemental　distributions　were　considered　crucial　to　understanding　the　failure　of　superalloys.　In　this　work,　initial　oxidation　behavior　in　typical　1st-　to　3rd-generation　single-crystal　superalloys　was　systematically　studied　in　situ　at　nanoscale　using　an　environmental　transmission　electron　microscope　from　20　to　800　degrees　C.　With　increasing　oxygen　pressure,　the　oxide　nucleated　at　the　gamma/gamma＇　interface,　expanded　along　the　c　channel,　and　grew　into　the　gamma＇　phase.　In　thin　foil　samples,　oxidation　prompted　the　diffusion　of　base　elements　from　the　inner　gamma　and　gamma＇　phases　to　the　gamma/gamma＇　interfaces　in　all　alloys.　With　increasing　Re　content,　the　oxidation　resistance　decreased　due　to　the　evaporation　of　Re2O7　at　the　gamma/gamma＇　interface　in　the　3rd-generation　superalloy.　This　study　provided　technical　guidance　for　optimizing　the　compositions　of　advanced　single-crystal　superalloys　to　enhance　their　oxidation　resistance.