A chain-tensioning rod (1), of the type used in an internal combustion engine with an overhead camshaft valvetrain to keep in tension a timing chain, comprising a shoe (4), which is pressed against the timing chain, and a supporting arm (25) of the shoe, allows a simple assembly of the arm and of the relative shoe because: the shoe (4) is formed by a monolithic piece having, on one side thereof, a sliding surface (5) and on, the opposite side, a supporting surface (6) and a contact element (7) connected to the supporting surface (6) by means of a longitudinal central rib (10); and the supporting arm (25) is formed by an elongated sheet having a longitudinal pass-through slit (27) extending from a distal end thereof, wherein it is open, so that the insertion of the supporting arm (25) on the supporting surface (6) takes place by making said rib (10) to slide in said slit (27), the rib (10) operating as transversal locking device of the supporting arm (25) on the supporting surface (6).