A variable-temperature single-pass absorption gas cell with an optical pathlength of 147.5 cm was designed and built for spectroscopicmeasurements of gases of atmospheric interest. The cell is optically matched to a Bomem DA8.3 Fourier transform spectrometer. Aheating/cooling system enveloping the cell, used together with a Neslab ULT-80 thermal bath, allows spectroscopic studies of gas samples attemperatures ranging from 205 to 350 K and at pressures up to 1 atm. Tests of the optical, thermal, and vacuum operation of the system wereperformed. Spectra of the 3ˆ0 vibrational–rotational band of carbon monoxide were recorded from 225 to 348 Kand used to determine therotational gas temperatures. These results were compared with values obtained using thermocouples, in order to assess the thermalperformance of the new system. A second temperature-controlled cell 25-cm long, able to withstand pressures up to 30 atm, was also used torecord CO spectra. We have recorded high-resolution FTIR spectra of CO and CO perturbed by N2 at temperatures from 295 to 348 K. Thespectra were analyzed to determine pressure broadening and pressure-induced shift coefficients, along with their temperature dependence forseveral transitions in the second overtone band of CO. The results, especially for self-broadening, are in excellent agreement with otherrecent measurements reported in the literature.q 2004 Elsevier B.V. All rights reserved.