A melting kettle for processing of thermoplastic material. The kettle disclosed herein obtains heat transfer by use of an oil jacketed tank with an adjoining main tank for storage of hot oil and a hose tank for recovery of the hot oil. Oil expelled from the oil jacket is directed to the main tank through an opening. Spillage of oil from the hose tank is directed to the main tank through an aperture. The melting kettle reduces the space needed for oil storage, and increases operator safety by eliminating additional transfer lines. Dual kettles benefit by having the adjoining main tank placed therebetween.