Abstract: Release mechanism for releasing a door-spring blocked by a blocking device, which mechanism comprises a temperature-sensitive control element for direct thermal actuation, by means of which the mechanism intervenes in the blocking device at a predetermined temperature of that element such that the door-spring is released. The release mechanism comprises for instance a rod guided for movement in longitudinal direction between a first end position and a second end position under a first bias in the direction to this first end position, and a control element comprising an SME material which at the predetermined temperature encloses the rod under a second bias greater than the first and in opposite direction thereto, which rod is coupled to a control member of the blocking device, which control member keeps the blocking device in operation in the first end position of the rod and renders the blocking device inoperative in the second end position of the rod.