The simulation of N-2(A(3) Sigma(+)(u)) and CO(a(3) Pi) vibrational populations at the altitudes of Titan's upper atmosphere and for conditions of a laboratory discharge in the N-2-CO mixture is made. The influence of metastable molecular nitrogen N-2(A(3) Sigma(+)(u)) on the electronic excitation of CO molecules in inelastic collisions is studied. It is shown that the increase in the density of the Titan's atmosphere and of the discharge mixture leads to more significant excitation of lowest vibrational levels of CO(a(3) Pi) by intermolecular electron energy transfers from N-2(A(3) Sigma(+)(u)) in comparison with direct excitation of the a(3)Pi state by free electrons. (c) 2017 Elsevier B.V. All rights reserved.