Abstract: A nozzle assembly for a plasma gun is disclosed, containing an annular coolant passage for extended nozzle life, providing for convenient and low cost replacement of the nozzle member and for improved gun operation. To form the assembly a jacket is disposed about the nozzle member in a predetermined coaxial position. An inner surface of the jacket cooperates with the cylindrical exteriority of the nozzle to define an annular coolant passage. The jacket and the nozzle are in relative slidable relationship such that the nozzle member is removable and replaceable forwardly with respect to the jacket, forwardly being in respect to the direction of the plasma flame. A flange at the forward end of the nozzle member retains the nozzle member from sliding rearward from the predetermined position with respect to the jacket. The jacket has coolant ports for the coolant connecting with the annular passage. A seal such as an O-ring is interposed between the rear portion of the nozzle and the jacket.