A dynamic system was developed and evaluated to continuously monitor product temperature in ovens using an aluminum shielded thermocouple. The signal was processed by a computer controlled feedback relay to turn the magnetron on or off relative to a preselected setpoint. Results indicated the temperature of water (> 100 mL) could readily be maintained within 1°C of the setpoint. Temperatures for small samples (∼5 mL) could also be controlled, however, they required use of an additional microwave heat-sink in the oven cavity to prevent temperature overshooting. The thermocouple based feed-back temperature control system worked well and provided a simple way to control sample temperature in a microwave oven.