Stimulated emission pumping has been employed to prepare specific Renner-Teller levels associated with the (0 12) vibrational manifold of the NCO((X) over tilde (2)Pi) molecule. Transfer out of these vibronic levels due to collisions with argon collision partner was monitored by laser fluorescence excitation. The total removal bimolecular rate constants were found to be large [(2-5) x 10(-10) cm(3) molecule(-1) s(-1)]. In several cases, it was possible to observe collisional transfer between specified (X) over tilde (0 1 2) Renner-Teller levels. The collisional transfer of population between the Renner-Teller levels was found to be a small fraction of the total collisional loss but was comparable in magnitude to the total decay rates for the (X) over tilde (0 1 0) levels. (C) 2003 Elsevier Science B.V. All rights