Proton　exchange　membrane　fuel　cells　are　widely　utilized　in　the　areas　of　aerospace,　military　and　vehicles.　Enhancing　the　reactant　transportation　and　improving　water,　heat　management　can　effectively　increase　the　electrochemical　reaction　rate　and　power　output.　Orientated-type　flow　channels　have　been　proved　to　be　effective　on　improving　mass　transporting　and　enhancing　performance.　In　this　study,　a　flow　field　plate　with　transparent　observation　window,　whose　channel　side　wall　is　designed　as　transparent　side-plates,　is　fabricated　to　achieve　the　side-view　observation　on　liquid　movement　behaviors　inside　fuel　cells.　The　visualization　results　of　reactant　gas　and　liquid　water　generation　and　flowing　behaviors　in　channel　regions　are　observed　through　the　side　direction　for　the　first　time.　Experimental　results　infer　that:　orientated-type　flow　channels　having　baffles　affect　droplet　generation,　moving　and　shape　in　gas　flow　channels,　and　higher　current　densities　result　in　more　liquid　water　generation.　The　baffle　downstream　region　having　sudden　expanded　region　slows　down　droplet　moving,　and　baffle　upstream　sides　accelerates　droplet　moving.　Moreover,　the　generated　heat　of　electrochemical　reaction　cannot　satisfy　maintaining　a　higher　cell　working　temperature　requirement,　and　an　extra　heating　procedure　is　required.(c)　2022　Elsevier　Ltd.　All　rights　reserved.