A device and method allow a dry catalyst to be delivered to a liquid-filled polymerization reactor, thus avoiding problems associated with catalyst-liquid contact or with undesired addition of gases to the reactor. A quantity of dry catalyst is transferred from a catalyst reservoir maintained under dry conditions to a catalyst chamber. An inert fluid then enters the chamber to flush the catalyst charge toward the reactor. Optional embodiments include means for precontacting the dry catalyst with a modifier and for removing gas from the fluid line.