Infrared spectrum of the weakly-bound CO$_2$--C$_2$H$_2$ complex in the region of the CO$_2$ $ν_3$ fundamental band ($∼$ 2349 cm$^{-1}$) is observed in a pulsed supersonic slit jet expansion using a tunable diode laser probe. Two bands are observed and analyzed: the fundamental (C--O asymmetric stretch) and a combination involving the intermolecular torsional (out-of-plane bend) vibration. The resulting torsional frequency is 44.385(10) cm$^{-1}$. This represents the first observation of an intermolecular frequency for carbon dioxide-acetylene complex. A comparison between the results obtained here and those previously reported for N$_2$O--C$_2$H$_2$ complex is discussed. ; Author Institution: Laboratoire de Chimie quantique et Photophysique, CP160/09 Faculte des Sciences, Universite Libre de Bruxelles (U.L.B.), Ave. Roosevelt, 50 B-1050 Brussels, Belgium; Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N; 1N4, Canada