Experiments were conducted on the vented explosion of hydrogen-air mixtures from a 1.5-m-long duct to a vented cylindrical vessel to investigate the effects of vent burst pressure and an obstacle in a 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 a duct to a vessel, the maximum reduced overpressure increased with an increase in the vent cover thickness. Although the maximum explosion overpressure was significantly less compared to an unvented explosion, it was still too high to be effective; therefore, it is recommended to fit an explosion vent in the duct. An obstacle installed in a duct significantly affected the explosion overpressure, which first increased and then decreased with an increase in the blockage ratio and the external flow field. Several pressure peaks resulting from different pressure waves were observed.