A sealing device producing sealed packages filled with pourable food product from sheet packaging material comprises a supporting frame, a forming mechanism movable with respect to the frame along a path to fold the sheet packaging material, a sealing arrangement carried by the forming mechanism to seal the sheet packaging material and form the packages, and an electromagnetic power device supplying electric energy to the sealing arrangement. The power device comprises at least one primary winding fixed to the frame and connectable to an electric energy source, and a secondary winding movable along the path, powering the sealing arrangement, and receiving electric energy by electromagnetic induction from the primary winding as the secondary winding travels past the primary winding. When interconnected by electromagnetic induction, the primary and secondary windings are so arranged as to have respective adjacent portions interjacent in a first direction crosswise to the forming mechanism movement path.