Plasma was generated in water by irradiation at high frequency of 13.56 MHz, and the behavior of bubbles including the plasma was observed by a high-speed camera. The generation pattern of the bubbles was classified into four types according to liquid temperature and supplied power. Conducting the simulation, the maximum temperature in the bubble was found to be from 3500 K to 4300 K. and the decomposition of water molecule occurred. The gas in the bubble was found to become high ratio of hydrogen. The phenomenon can be regarded as a film boiling of exceptionally high heat flux. (C) 2010 Elsevier Ltd. All rights reserved.