Fourier-transform absorption spectroscopy has been used in the laboratory to obtain absolute absorption coefficients &sgr;(&ngr;) in infrared bands of ClONO2 in the 700--1800 cm-1 spectral region. These data have been obtained over a temperature range (213--296 K) corresponding to stratospheric temperatures. The results are therefore applicable to retrievals of stratospheric ClONO2 from remote-sensing observations. Room temperature absorption coefficients are some 25% larger than previously reported values, and large temperature dependences in the absorption coefficients have been observed. The &ngr;1 and &ngr;2 bands behave as simple fundamentals of a system which has low-energy vibrational or torsional modes, with little contribution from hot bands over the temperature range used. The intensity in the &ngr;2 Q branch increased by 53% over the temperature range 296--213 K. A similar increase was observed for the &ngr;4 Q branch, and significant hot-band features were seen in the &ngr;3, &ngr;4 spectral region. The &ngr;4Q branch and the &ngr;2 Q branch were observed to obey the Beer Lambert law over the range of pressure, temperature, absorber, amount, and resolution employed. The absorption coefficients in the &ngr;4 Q branch and in the &ngr;2 band were modeled by equispaced absorption lines, each characterized by a central freuqency, strength, lower-state energy, and pressure-broadened width. ¿ American Geophysical Union 1988