The present invention is directed to A method of making a cord-reinforced rubber article, comprising the steps of A) mixing a carrier gas, sulfur and an alkyne, to form a gas mixture; B) generating an atmospheric pressure plasma from the gas mixture; C) exposing a reinforcement cord to the atmospheric pressure plasma to produce a coated reinforcement cord; and D) contacting the coated reinforcement cord with a rubber composition comprising a diene based elastomer.