Infrared thermography is a thermal measurement process that produces images in which each pixel contains a temperature measurement. This technique is very popular in many industries and fields such as preventive and/or predictive maintenance and non-destructive testing, to detect problems more efficiently and safely, but is not currently used effectively. [1] Techniques and technical applications are developed, for the detection and analysis of a certain defect on electronic circuits and electrical equipment. Current thermographic processing software has some limitations, mainly because it is developed for general applications and does not identify a region of interest. The identification of a region of interest with a particular anatomical shape. These shapes are limited when they do not correspond to the complex geometric shape of the area to be characterized, either by exclusion or inclusion of irrelevant data in the evaluation of thermal images. This restriction is observed regardless of the accuracy of the region of interest. This paper presents an image processing technic for localization of MOSFET faults based on thermal, hence the use of segmentation algorithms increases the accuracy of the thermal image analysis.