A microcomputer-based system was developed for the control of temperature from 199.9.degree. to -199.9.degree. C, and rate of change of temperature from 0.01.degree. to 99.99.degree. C/min. A digital thermometer is used to monitor the temperature; the system can control a variety of heating and cooling equipment. The system is economical, easy to construct, simple to program and may be extended to perform a wide variety of functions based on the control of temperature.