The Microwave Thermography System consists of two microwave radio sensors (microwave probes), a microwave radio-receiver unit, two digital pyrometers fitted with rigid electrical thermocouples, and an electronic data logger compatible with a chart-recorder and micro-computer with a built-in analogue-to-digital converter (ADC). The microwave probes were used in the current study to monitor the brain and liver temperatures, and the thermocouples were used to monitor the rectal and environmental temperatures. The current study was conducted in the Glasgow City Mortuary during 1983-86. A total of 117 forensic postmortem cases were studied under controlled conditions. In each case, temperatures of the brain, liver, rectum, and the environment were monitored over a period that began shortly after death and ended up to 60 hours postmortem. The four temperature measurements were recorded every 5 to 10 minutes. The data were transferred to a mainframe computer for extensive curve-fitting and statistical analysis. The micro-computer based ADC and data logging and acquisition were found to be accurate, fast, easy to implement, and useful for the field. The postmortem rate of human body cooling was found to be adequately represented by triple-exponential equations. 3 tables, 2 figures, and 30 references