This is a low-cost microcontroller-based project among all the Sensor based project ideas. Microcontroller based Overheat detector using Temperature sensor with Buzzer indication has applications in various areas including Industrial application, and domestic application. A temperature sensor is used to detect overheating conditions. The output of the temperature sensor is given to Comparator. And the output of the comparator IC is given to microcontroller 89s51. Liquid crystal display – LCD display shows a message when Temperature crosses the threshold level. And also a Buzzer is turned on to give an overheat indication. We have provided a potentiometer which is used to vary the threshold level of the comparator which decides the threshold level of an overheat condition.