Amplification of 10.6-μm radiation in a metallic waveguide and waveguide CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -laser action was achieved by excitation of the CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> (00 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> 1) mode by vibrational energy transfer from metastable <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N\min{2}\max{\ast}(\upsilon = 1)</tex> molecules. Excitation of N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> was accomplished in a separate dc discharge tube. The N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -He mixture, after flowing through the discharge region, was pumped into the waveguide and there CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> was added. Maximum small-signal gain values of 25.6 and 15.3 dB/m were obtained at amplifying waveguide sections of 2 and 6-cm length, respectively. A theoretical analysis, based on rate equations for the (00 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> 1) and the (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> 0) states of CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and the concentration of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N\min{2}\max{\ast}(\upsilon = 1)</tex> molecules, is presented, which leads to predictions for the small-signal gain and the saturation intensity. In the pressure range covered by experiments the calculated gain values were found to be consistent with measurements.