A vascular occlusion device deployment system for placing an occlusion device at a preselected site within the vasculature of a patient. The deployment system employs a pusher including a gripper located at the distal end of the pusher to releasably retain a vascular occlusion device. The gripper is expanded by an expandable chemical reaction chamber so that the gripper releases the vascular occlusion device, thereby deploying the vascular occlusion device. In one embodiment, a vascular occlusion device deployment system, comprises: a vascular occlusion device having a protruding portion a deployment unit comprising a pusher having a proximal end portion and a distal end portion an expandable gripper located at the distal end portion of the pusher, the gripper including an outwardly expandable gripping element for gripping the protruding portion of the vascular occlusion device and an expandable reaction chamber located within the gripper, said chamber expanding upon a reaction of at least a first reactant and a second reactant within an interior cavity of the chamber whereby the expansion of the chamber causes the gripper to outwardly expand, releasing the protruding portion of the vascular occlusion device.
