This study presents the thermal characteristics of a fin with excavation at base when various types of boiling occur simultaneously at adjacent locations on its surface experimentally and analytically. The heat transfer coefficient of each boiling mode is taken as a power function of wall superheat. Continuity of temperature and the heat transfer rate at the intersection of the two different modes on fin surface are employed to obtain the one-dimensional temperature distribution and total heat transfer of the excavated fin. Both heating and cooling cases are investigated in the analysis. Compared with solid pin fins, the proposed fins can extend the operating condition to a higher temperature of the heat transfer surface. In addition, the experimental data compare favorably with the analytical results. (c) 2005 Elsevier Ltd. All rights reserved.