A deep resistivity study of Kilauea volcano using the controlled-source electromagnetic (CSEM) technique has revealed that the summit region (i.e., the area bounded by the east rift zone, the southwest rift zone, and the Koa'e fault zone) consists of subhorizontal layers having resistivities ranging from 2 ohm-m to greater than several hundred ohm meters. The vertical sequence of resistivities is consistent with an increase in temperature from 20 ¿C at the surface to over 1000 ¿C at the depth of about 5 km. Temperatures beneath the adjacent but inactive area of Mauna Loa probably do not exceed 300 ¿C at a comparable depth. A deep conductor, which is indicated by data at five observation locations on Kilauea, may be magma. The source for the CSEM study is a horizontal wire square approximately 2 km on a side, through which a sinusoidal current of about 80 A (peak-to-peak) is driven at frequencies between 0.04 and 8 Hz.