Thermally-activated pressure relief devices (TPRD) with glass bulbs or fusible alloy are applied to high-pressure hydrogen storage cylinders (HHSC), in order to release hydrogen gas from the cylinder in fire accidents. In this paper, cylinders with different TPRDs were tested in two groups using different bonfire test methods. In group A, the fire was set exactly under the TPRD. While in group B, the fire was set 80 mm beside the TPRD. The result shows that TPRDs with glass bulb and fusible alloy acted in a similar way when the fire was under the cylinder and the TPRD. However, they acted in a quite different way when the fire was only under the cylinder and beside the TPRD. In group A, hydrogen was released continuously from TPRD both for glass bulb and fusible alloy. In group B, hydrogen was released continuously from the TPRD using glass bulb which was similar to the group A. However, for TPRDs using a fusible alloy, hydrogen was released in several stages taking much more time. The results are instructive for the design and selection of TPRDs on HHSC.