We have tested a suite of micromachined chemical sensors on STS-93. This experiment is one of several incorporated in the overall Micro/Nano Technology (MNT) Testbed developed at The Aerospace Corporation. The sensors used in this experiment include: (1) a micromachined interferometer for carbon dioxide (CO2) detection, (2) a palladium thin-film sensor for hydrogen (H2), (3) a micromachined, micro hot plate sensor for carbon monoxide (CO), (4) a micromachined strain gauge pressure sensor, and (5) networked digital thermometers. A gas dosing system to test the sensors in flight was also included. The experimental design and flight results are presented and discussed.