Abstract: A miniature gas chromatograph with thermostatically-controlled heating of its component parts which contact and conduct the sample to the analytical column. The microvalve assembly of the gas chromatograph is heated by passing a thermostatically-controlled electrical current through a metallic conductor formed on a surface of the microvalve assembly. The tubing which conducts sample from the gas chromatograph sample inlet to the microvalve assembly is heated by passing a thermostatically-controlled electrical current directly through the tubing or through a metal layer formed around the tubing. The sample inlet fitting is heated by a wire heater element wrapped around it. Each heater has an associated temperature sensor for controlling the amount of heating to maintain a predetermined temperature.