The characteristics of the active medium of a CO//2 laser were studied. The laser was excited by a nonself-sustained combined discharge with ionization of the medium by short electrical pulses in a CO//2-N//2-He gas mixture stream. The dependences of the ultimate input energy, gain, and heating of the gas on the composition of the gas mixture were determined. It was shown that using this pumping method a specific input energy of approximately 450 J/g could be reached, with an efficiency for the excitation of vibrations in the nitrogen and in the carbon dioxide gas of approximately 90%.