The COS+à 2II-X̃ 2II emission bands between 3500 and 6500 Å have been observed following vuv photon impact on COS. Only the v′ = 0 progression is found to occur for incident vuv photons in the energy range 15.11-20.3 eV. The absence of emission from the higher vibrational levels is interpreted as evidence of pre-dissociation of the à 2II state into CO(X1Σ+) +S +(2D0) components.