Abstract: A catalyst unloading mechanism for unloading catalyst and inert materials from catalyst tubes or passages within a catalytic reactor. The mechanism is separatable into major sections, the size of which is sufficiently limited as to facilitate passing the same through the mayway of a reaction vessel for assembly inside the vessel. A plurality of probes which may be fed from a spool are at least partially oscillated by an oscillating frame and are inserted into the catalyst tubes or passages while oscillating by a movable support frame so as to dislodge catalyst and inert materials contained within the tubes or passages. A collector tray through which the probes extend functions to collect material dislodged by the probes and diverts it to an outlet opening for collection.