The invention relates to a device for the continuous, homogeneous-catalysis reaction of a liquid with a gas and optionally an additional fluid, wherein the device comprises at least one reactor having an external liquid circulation driven by a pump, and wherein the device has at least one membrane separation stage that preferably holds back the homogeneous catalyst. The aim of the invention is to specify a device that allows homogeneous-catalysis gas/liquid phase reactions, in particular hydroformylations, which operate with membrane separation of the catalyst to be performed economically at an industrially relevant scale. Said aim is achieved in that a jet loop reactor is provided as the reactor, and that the pump and the membrane separation stage are arranged in the same external liquid circuit.