Cytochrome c-oxidase, used as a model membrane-bound enzyme, was embedded in phospholipid bilayer membranes, attached to nanometer-sized Fe3O4 colloids (so-called magnetoliposomes). In comparison with the lipid-depleted free enzyme, both the activity and the enzymatic stability of the complexes, stored at 4 degrees C, were considerably enhanced. These beneficial properties of magnetoproteoliposomes have been successfully exploited in a magnetically controlled fixed-bed bioreactor, operating in a continuous flow regime.