We　report　measurements　of　the　diffusion　of　atomic　hydrogen　in　single　crystalline　VO2　micro/nanobeams　by　direct　exposure　to　atomic　hydrogen,　without　catalyst.　The　atomic　hydrogen　is　generated　by　a　hot　filament,　and　the　doping　process　takes　place　at　moderate　temperature　(373　K).　Undoped　VO2　has　a　metal-to-insulator　phase　transition　at　?340　K　between　a　high-temperature,　rutile,　metallic　phase　and　a　low-temperature,　monoclinic,　insulating　phase　with　a　resistance　exhibiting　a　semiconductor-like　temperature　dependence.　Atomic　hydrogenation　results　in　stabilization　of　the　metallic　phase　of　VO2　micro/nanobeams　down　to　2　K,　the　lowest　point　we　could　reach　in　our　measurement　setup.　Optical　characterization　shows　that　hydrogen　atoms　prefer　to　diffuse　along　the　c　axis　of　rutile　(a　axis　of　monoclinic)　VO2,　along　the　oxygen　channels.　Based　on　observing　the　movement　of　the　hydrogen　diffusion　front　in　single　crystalline　VO2　beams,　we　estimate　the　diffusion　constant　for　hydrogen　along　the　c　axis　of　the　rutile　phase　to　be　6.7　x　1010　cm2/s　at　approximately　373　K,　exceeding　the　value　in　isostructural　TiO2　by　?38x.　Moreover,　we　find　that　the　diffusion　constant　along　the　c　axis　of　the　rutile　phase　exceeds　that　along　the　equivalent　a　axis　of　the　monoclinic　phase　by　at　least　3　orders　of　magnitude.　This　remarkable　change　in　kinetics　must　originate　from　the　distortion　of　the　channels　when　the　unit　cell　doubles　along　this　direction　upon　cooling　into　the　monoclinic　structure.　Ab　initio　calculation　results　are　in　good　agreement　with　the　experimental　trends　in　the　relative　kinetics　of　the　two　phases.　This　raises　the　possibility　of　a　switchable　membrane　for　hydrogen　transport.