In　this　work,　proton　exchange　membrane　fuel　cells　(PEMFCs)　with　transparent　windows　are　designed　to　study　the　gas-liquid　two-phase　flow　behaviors　inside　flow　channels　and　the　performance　of　a　PEMFC　with　vertical　channels　and　a　PEMFC　with　horizontal　channels　in　a　normal　gravity　environment　and　a　3.6　s　short-term　microgravity　environment.　Experiments　are　conducted　under　high　external　circuit　load　and　low　external　circuit　load　at　low　temperature　where　is　35　degrees　C.　The　results　of　the　present　experimental　work　demonstrate　that　the　performance　and　the　gas-liquid　two-phase　flow　behaviors　of　the　PEMFC　with　vertical　channels　exhibits　obvious　changes　when　the　PEMFCs　enter　the　3.6　s　short-term　microgravity　environment　from　the　normal　gravity　environment.　Meanwhile,　the　performance　of　the　PEMFC　with　vertical　channels　increases　after　the　PEMFC　enters　the　3.6　s　short-term　microgravity　environment　under　high　external　circuit　load,　while　under　low　external　circuit　load,　the　PEMFC　with　horizontal　channels　exhibits　better　performance　in　both　the　normal　gravity　environment　and　the　3.6　s　short-term　micro　gravity　environment.　(C)　2017　Elsevier　B.V.　All　rights　reserved.