A comparison study is conducted to reveal the differences of hazard distances and accident durations between hydrogen vehicles and CNG vehicles during a representative accident in an open environment, i.e gas release from thermally-activated pressure relief device (TPRD). The analysis is performed for the scenario of impinging jet fires released from 4.2 mm TPRD diameter, with release inventory assumption on the basis of similar driving range: 4 kg hydrogen storage at 35 MPa and 20 kg methane storage at 25 MPa. Results show that the release duration for CNG vehicle is over two times longer than that for hydrogen vehicle, indicating that CNG vehicle jet fire accident is more time-consuming and firefighters have to wait a longer time before they can safely approach the vehicle. For both hydrogen vehicle and CNG vehicle, the longest hazard distance near the ground occur at a few seconds after the initiation of the TPRD. Afterwards the flames will shrink and the hazard distances will decrease. For firefighters with bunker gear, they must stand at least 6 m and 14 m away from the hydrogen vehicle and CNG vehicle, respectively. For general public, a perimeter of 12 m and 29 m should be set around the accident scene for hydrogen vehicle and CNG vehicle, respectively. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.