Molecular　hydrogen　has　been　shown　to　exert　beneficial　effects　on　plant　growth　and　abiotic　stress　tolerance,　however,　the　exact　mechanism　has　not　yet　been　fully　elucidated.　H-2　is　able　to　diffuse　directly　across　the　plasma　membrane,　which　is　the　first　barrier　between　H-2　and　cells.　It　is　possible　that　H-2　may　exert　its　biological　effects　on　plant　cells　by　interacting　with　PM.　Hydrogenases　can　catalyze　the　reversible　reaction　of　dihydrogen　into　protons　and　electrons,　which　has　been　found　in　microbes　and　rarely　reported　in　higher　plants.　We　speculated　that　the　hydrogenase　activity　may　also　exist　in　the　PM　of　higher　plants,　and　the　potential　PM　hydrogenases　may　act　as　an　electron/proton　provider　or　acceptor　for　H-2　metabolism,　which　makes　H-2　a　modulator　of　redox　homeostasis.　The　potential　hydrogenase　activity　of　the　PM　vesicles　of　two　higher　plants　species　were　determined　by　real-time　spectrophotometry,　gas　chromatography,　and　H-2　sensor　detection.　The　results　showed　that　both　H-2-evolving　and　H-2-uptake　activities　existed　in　PM　vesicles　of　both　V.　radiata　hypocotyls　and　Capsicum　annuum　stems.　This　hydrogenase　activity　is　coupled　with　the　redox　reactions　of　ferricyanide/ferrocyanide　and　NADH/NAD(+).　The　net　H+,　Na+,　and　K+　fluxes　of　V.　radiata　hypocotyls　were　measured　using　Non-invasive　Micro-test　Technology　(NMT).　The　results　showed　that　H-2　could　prompted　H+　effluxes,　which　may　contribute　to　the　significant　elongation　of　V.　radiata　hypocotyls.　Under　salt　stress,　H-2　significantly　promoted　H+　effluxes　and　reduced　Na+　influx,　indicating　that　the　transport　of　salt　ions　across　the　membrane　could　be　affected　by　H-2　in　PM　vesicles.　These　results　demonstrate　that　the　hydrogenase　activity　may　be　widely　existed　in　higher　plants＇　PM　vesicles,　and　H-2　could　affect　the　proton　gradient　and　regulate　redox　processes　in　plant　PM,　which　may　be　responsible　for　its　effects　on　iron　transport　and　other　physiological　and　pathophysiological　processes.