This paper describes a dual‐beam, tunable diode laser (TDL) spectrometer built for gas‐phase vibrational spectroscopy studies. It employs a commercially available cryogenic cooler and control electronics and can incorporate Pb‐salt diode lasers with operating wavelengths from 7 to 12 &mgr;m. The instrument optics have been largely assembled using inexpensive reflecting components. An IBM personal computer with enhanced graphics and high‐speed data‐acquisition unit permits dual‐channel sweep averaging (normally done with expensive, commercial hard‐wired units) as well as on‐line spectral line parameter calculations. Such an arrangement puts this type of laser spectroscopy capability within reach of undergraduate physics and chemistry programs.