An interface and gas chromatograph oven are described that permit repetitive separation and mass spectrometric analysis of evolved gases generated during solid sample thermal decompositions. Examples of the use of this apparatus for identifying the volatile products generated by heating poly(vinyl butyral), thermally desorbing 1-butene oligomers from sulfated zirconia, and by cracking poly(styrene) with HY zeolite are described. Evolved gas analyses employing rapid temperature programmed capillary gas chromatography and subambient column temperatures are demonstrated. Species-specific evolution profiles are generated by integrating peaks that correspond to the same substance in successive chromatograms.