An apparatus determines cooling characteristics of an operational cooling device used for transferring heat from an electronic device. The operational cooling device is thermally coupled to a heat pipe. The heat pipe has an exposed surface for selective application of heat thereon. Heat from a localized heat source is selectively applied to at least one region of the exposed surface. The heat source is preferably capable of being varied both positionally relative to the exposed surface and in heat intensity. A heat shield is preferably positioned around the exposed surface of the heat pipe to isolate the operational cooling device from the heat from the localized heat source. A temperature detector repeatedly measures a temperature distribution across the exposed surface while the cooling device is in a heat transfer mode. The temperature distribution is then used to thermally characterize the operational cooling device.