Amongst　the　structural　materials　for　high　temperature　applications　that　are　currently　in　the　focus　of　research,　high　entropy　alloys　(HEAs)　exhibit　very　promising　features,　such　as　high　strength,　good　fracture　toughness,　high　temperature　phase　stabilities　and　excellent　resistance　against　softening　at　elevated　temperatures.　Key　influencing　factors　for　high　temperature　applications　are　the　mechanical　properties　at　elevated　temperatures　as　well　as　the　oxidation　behavior　of　a　given　material.　AlxCrFeCoNi　alloys　have　been　mostly　investigated　among　different　HEAs.　However,　up　to　now　there　are　limited　reports　dealing　with　the　oxidation　behavior　of　AlxCrFeCoNi-based　HEAs,　especially　with　respect　to　the　effect　of　Si-alloying　on　the　oxidation　behavior　at　elevated　temperatures.　In　this　study,　the　oxidation　behavior　of　two　HEAs,　Al0.6CrFeCoNi　and　Al0.6CrFeCoNiSi0.3,　were　comparatively　investigated　at　T　=　800　degrees　C,　900　degrees　C　and　1000　degrees　C　in　air　to　determine　the　effect　of　Si-alloying.　The　results　show　that　oxidized　layers　typically　consist　of　Cr2O3/spinet　and　Al2O3　with　an　underlying　Al-depleted　zone.　AlN　was　found　inside　the　Al-depleted　zone　with　the　exception　of　Al0.6CrFeCoNiSi0.3　oxidation　at　T　=　800　degrees　C.　However,　Si　alloying　only　positively　influenced　the　oxidation　behavior　at　T=　800　degrees　C.　Here,　it　promoted　the　formation　of　a　continuous　Al2O3　layer.　The　Si-alloying　did　not　enhance　the　oxidation　resistance　at　T　=　900　degrees　C　and　1000　degrees　C.　(C)　2018　Elsevier　B.V.　All　rights　reserved.