In the studies on the stability of biocatalysts in a high-pressure batch stirred tank reactor, changes in biocatalyst activity due to pressurization/depressurization steps were observed. An interesting alternative to overcome this inconvenience is using the high-pressure continuous membrane reactors, where just a single compression and expansion step is necessary. The aim of the research was to carry out the enzyme-catalyzed reactions in high-pressure membrane reactors. At first, high-pressure enzyme-catalyzed hydrolyses of oleyl oleate and sunflower oil were performed in a high-pressure continuous enzymatic flat-shape membrane reactor. Additionally, cellulase from Humicola insolens was covalently immobilized on tubular membrane, and enzyme-catalyzed hydrolysis of carboxy-methyl cellulose was carried out in a high-pressure continuous enzymatic tubular membrane reactor. The membrane-stability tests for flat-shape polysulfon membranes before and after treatment with supercritical CO2 or subcritical propane were done, as well.