An induction sealing device which may be used for producing packages of pourable food products by transversely sealing a tube of sheet packaging material having at least one layer of induction heatable material covered with plastic material. The sealing device has: a generator for generating an alternating power signal; an inductor receiving the alternating power signal to induce a parasitic electric current in the layer and locally melt the plastic material to form a transverse seal; and a matching circuit for achieving optimum power transfer between the generator and the inductor. The matching circuit includes an inductive-capacitive circuit, in which the capacitance of a variable capacitance capacitive element is adjustable so that the current-voltage phase angle is close to zero.