A H2/Ar cascaded arc plasma source has been experimentally characterized by determination of the efficiency, the electric field, and the pressure gradient of the arc. The results show that the efficiency of a H2/Ar cascaded arc drops when the hydrogen flow rate is increased. The electron temperature in the argon cascaded arc has been derived to be in the range 9000–12 500 K. For a hydrogen arc, the mass dissociation degree of hydrogen molecules has been derived to be above 60%.