A thermal cycler fabricated with low temperature, co-fired, ceramic tapes is described. The monolithic device consisted of a flow conduit, a resistor (Joule) heater, a thermistor, and conductors. A microprocessor was used to control the device’s temperature according to a pre-programmed temperature protocol. The device’s thermal performance was modeled, and the theoretical predictions were compared with experimental observations. As an example of an application, the device was used to carry out a polymerase chain reaction in which a non detectable concentration of a DNA segment was sufficiently amplified so as to enable separation and detection by electrophoresis.