Oxygen　side　flow　channel　structures　have　significant　influence　on　the　dynamic　response　of　relevant　parameters　in　operation　mode　switching　procedures　of　a　unitized　regenerative　fuel　cell.　In　this　paper,　an　unsteady,　non-isothermal,　two-phase,　two-dimensional　unitized　regenerative　fuel　cell　model　is　established　to　study　the　dynamic　response　of　two-phase　species　concentration　distributions,　current　density　distributions　etc.　when　the　cell　mode　swiches　from　the　fuel　cell　mode　to　the　electrolyzer　when　using　orientational　flow　channel　at　the　oxygen　side.　The　influence　of　eight　oxygen-side　channels　on　the　mode　switching　process　is　compared.　Results　show　that　the　required　time　for　each　parameter　reaching　the　stable　state　in　the　fuel　cell　mode　is　longer　than　the　dynamic　response　time　after　switching　to　electrolytic　cell　mode　when　using　orientational　flow　channels.　In　addition,　different　flow　channel　structures　at　the　oxygen-side　affect　the　time　requirement　for　stabilizing　each　parameter　during　mode　switching,　while　they　do　not　change　the　characteristics　of　the　stable　state　mode.(c)　2022　Elsevier　Ltd.　All　rights　reserved.