Graphene　and　its　oxides　are　the　most　extensively　studied,　fascinating　2-dimensional　Sp(2)　carbon　hybridized　materials.　Due　to　its　superior　and　excellent　thermal　conductivity,　it　is　considered　to　be　a　practical　solution　for　the　thermal　dissipation　of　electric　machines　electronic　components.　Furthermore,　graphene　oxide　invariably　reduces　electrical　insulation　capability,　which　is　inappropriate　for　electrical　machines　requiring　low　electrical　and　high　thermal　conductivity.　Therefore,　we　have　created　2D-3D　hybrid　graphene　oxide　(GO)-diamond　(DM)　micro-composite　polyimide　(PI)　films　for　high　temperature　and　electrically　insulated　environments　of　electric　machines　such　as　motors　and　generators.　With　a　modest　filling　charge　of　10　wt%　GO　with　10%　diamond　(DM),　the　maximum　thermal　conductivity　of　1.83　Wm(-1)K(-1)　is　achieved　for　polyimide　micro　composite　and　is　almost　11　times　higher　than　that　of　pristine　PI　films.　The　10%　PI/GO/DM　micro　composite　films　also　show　lower　electrical　conductivity　than　other　samples.　Hybrid　fillers　with　high　thermal　and　low　electrical　conductivities　are　responsible　for　synergistic　improvements　in　experimental　results.　(C)　2022　The　Korean　Society　of　Industrial　and　Engineering　Chemistry.　Published　by　Elsevier　B.V.　All　rights　reserved.