Experiments　were　conducted　on　the　vented　explosion　of　hydrogen-air　mixtures　from　a　150-cm-long　duct　to　a　cylindrical　vessel　with　a　vent　at　the　center　of　its　side　wall　to　investigate　the　effects　of　vent　burst　pressure　and　an　obstacle　in　duct　on　the　process　of　explosion　venting.　Turbulent　pressure　oscillation　owing　to　a　pressure　wave　moving　back　and　forth　in　a　duct　and　vessel　was　observed　for　unvented　explosions.　For　explosion　venting　from　duct　to　vessel,　flame　acceleration　in　duct　much　increases　the　explosion　overpressure　in　vessel.　The　maximum　explosion　in　duct　is　always　higher　than　that　in　vessel,　and　both　of　them　increase　with　an　increase　in　the　vent　cover　thickness.　An　obstacle　installed　in　duct　significantly　affected　the　explosion　overpressure,　which　first　increased　and　then　decreased　with　an　increase　in　the　blockage　ratio.　Three　pressure　peaks　were　distinguished　in　the　external　pressure-time　histories,　which　were　resulted　form　different　pressure　waves　formed　outside　the　vessel.　(C)　2018　Hydrogen　Energy　Publications　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.