Abstract: An ebulliometric hot spot detector detects hot spots with a resolution of the order of a micron on semiconductor devices. The device to be tested is operated in a suitable liquid contained in the detector, and the liquid pressure is decreased until boiling from sites on the device is observed. The liquid pressure is then increased until boiling ceases; meanwhile, the boiling sites on the device are observed. Small bubbles observed just before cessation of boiling pinpoint the hot spot locations. The pressure at which boiling ceases in a given liquid determines the hot spot temperature.