IR detector is characterized using the blackbody radiation for the temperature range of 300–373 K. The experimental set-up consists of IR lamp coated with black paint leaving 1 cm2 blank area as a black body source. This black body was positioned exactly above the sensing device (i.e. thick film thermistor) such that the IR rays exactly falls on the device. Temperature of the blackbody as well as the sensing element was measured using Agilent make J-type thermocouple. The experimental set-up used for IR detection and measurement is shown in Fig. 1. The sensor response to IR radiations was measured by positioning the detector at different distances of 1–5 cm from the blackbody. As the temperature of the black body increases, the resistance of the sensing element changed due to the absorbed radiant heat. The data of change in resistance, detector (sensing element) temperature and black body temperature was collected using the Agilent data acquisition system (model 34970A).