Aligned polymeric nanofibers obtained via electrospinning were sputter-coated with metals on both their front and back sides. When both sides were coated with the same metal (gold, silver or platinum/palladium alloy), the nanofibers behaved as pure conductors. However, coating front and back of the fibers with different metals causes a potential difference when they are immersed in an aqueous solution. This potential difference propelled the Janus fibers in the direction perpendicular to their long axis when hydrogen peroxide was present in the solution.