Abstract: The invention relates to a reductant supply system for a waste gas cleaning catalyst (1) of an internal combustion engine, particularly a motor vehicle, comprising a reductant tank (3) for the storage of reductants, at least one electrically heatable fluid duct (6, 8) for the conveyance of reductant from the reductant tank (3) to a waste gas cleaning catalyst (1), a pump (5) to pump the reductant via the fluid duct (6, 8) from the reductant tank (3) to the waste gas cleaning catalyst (1), and a plug-in connection (10, 11) for connecting sections of the fluid duct (6, 8) in a fluid-conveying manner and/or connecting the fluid duct in a fluid-conveying manner to a component of the reductant supply system, wherein the plug-in connection additionally forms an electric connection line (12, 13, 14) which in operation conveys an electrical heating current for heating of the fluid duct (6, 8).