A reactor installation tool and method for installing a reactor unit in a reactor tube. A reactor installation tool including a movable assembly and a fixed assembly linked together such that the movable assembly can be adjusted relative to the fixed assembly. The movable assembly including a reactor sleeve attachment means for releasably securing a reactor sleeve loaded with a reactor unit to the tool. The fixed assembly including an expandable clamping unit for releasably securing the tool to a reactor tube. A reactor unit can be installed in the reactor tube by adjusting the movable assembly to extract the reactor unit from the reactor sleeve as the fixed assembly is rigidly secured to the reactor tube. The fixed assembly can be released from the reactor tube and the reactor installation tool can be removed from the reactor tube.