In　situ　environmental　transmission　electron　microscopy　has　previously　been　applied　to　traditional　alloys　and　has　been　verified　as　a　powerful　tool　for　studying　oxidation　mechanisms.　Single-crystal　Ni-based　superalloys　are　often　used　for　commercial　turbine　blades,　especially　1st-　to　3rd-generation　superalloys.　The　reactivity　to oxidation of　the　single-crystal　Ni-based　superalloys　was　the　main　factor　in　deciding　their　bulk　oxidation　resistance.　An　overall　study　on　different　generations　of　various　Re-containing　Ni-based　superalloys　was　conducted　in　this　study　to　compare　their　difference　in　oxidation　properties　using　an　in　situ　technique.　Nanoscale　structural　and　elemental　distributions　across　the　γ/γ′　interface　were　assessed　on　three　typical　1st-　to　3rd-generation　superalloys　via　modern　electron　microscopy.　Oxidation　at　the　γ/γ′　interface　was　systematically　analysed　by　an　in　situ　oxidation　process　in　an　environmental　transmission　electron　microscope　to　reveal　the　nanoscale　oxidation　mechanisms　and　the　roles　of　key　elements.　Preferential　oxidation　of　the　γ/γ′　interface　is　revealed　in　oxidation　mechanisms.　Aggregation　of　Cr　and　Re　in　the　γ/γ′　interfaces　of　the　0Re　and　7Re　alloys　induced　a　larger　lattice　misfit　and　a　corresponding　stress,　which　prompted　priority　oxidation　at　the　interface.　Key　factors,　including　alloy　elements　and　microstructures,　are　extracted,　and　this　technique　is　expected　to　be　applicable　to　more　materials.　©　2022,　The　Author(s),　under　exclusive　licence　to　Springer　Science+Business　Media,　LLC,　part　of　Springer　Nature.