Kappaphycus alvarezii or commonly known Eucheuma cottonii is a source of kappa-carrageenan and could find cultivated in the coastal areas of Indonesia especially in Lontar Banten province. Kappaphycus alvarezii is one type of red seaweed contained kappa carrageenan. Lontar beach in Banten province is one that produced red seaweed In Indonesia. Refined Carrageenan could be used as a stabilizer, thickener, gel, medicine, cosmetics, etc. An important factor affected the production of refined carrageenan one of them is the temperature and extraction method. In this study refined carrageenan extracted used the ultrasonic irradiation method from Kappaphycus alvarezii originated from coastal lontar has never been studied. This research aimed to determined the effect of temperature using ultrasonic irradiation. The result indicated that higher temperature increased of the sulphate content, gel strength, gelling point and ash content but reduced in moisture and yield. This study the best temperature extraction is 700 C.