The quenching of vibrationally excited NO+ by O-2(a (1)Delta(g)) has been examined using the monitor ion technique and chemical generation of O-2(a (1)Delta(g)). In contrast to previous results which showed that the rate constant was much larger than for ground state O-2, this study finds that the rate constant for quenching is below the detection limit (<10(-11) cm(3) s(-1)) of this experiment. The previous experiments produced O-2(a (1)Delta(g)) in a discharge, which would also produces O atoms. We found that the monitor ion CH3I+ reacts with O atoms to produce CHIOH+. This is the likely cause of error in the previous experiments.