Nanoscale devices for energy conversion require the transfer of electrons from one compartment to another. The enzyme complex I, which in vivo mediates electron transfer from NADH to ubiquinone, is an intriguing candidate for this role in nanodevices. However, complex I normally requires the presence of lipids to remain active, potentially limiting its application. Here we demonstrate for the first time that complex I can be actively reconstituted in the synthetic membrane of amphiphilic triblock copolymer vesicles. The functionality of the reconstituted protein was characterized by EPR and activity assays. Its activity is strongly influenced by the molar mass and the block length of the membrane-forming polymers, and increases with increasing membrane thickness.