Abstract-In this brief, we present a novel noninvasive method for spatially resolved thermal measurement of HEMT devices based on microphotoconductance analysis. This approach is used to obtain the temperature distribution in the active regions of a GaAs P-HEMT. Through 1-D and 2-D thermal maps, we are able to measure the temperature inside each single channel, and owing to the improved spatial resolution of the developed technique, it is possible to observe the hottest region of the device which is placed at the drain side of the gate. Moreover, the resolution of the temperature measurements allows to define a local thermal resistance which is not uniform over the device due to the mutual heating between the channels.