Quenching studies of the NO B 2Π state with NO X 2Π and O2 X 3Σ-g colliders have been carried out for the vibrational levels v’=0–3 and 7. NO B 2Π was generated by laser excitation, and the temporal fluorescence decays were found to be single exponentials. The decays are predominantly due to quenching to dark states, and show little vibrational transfer or transfer into A 2Σ+. The quenching rates for NO do not show a change with v, and have an average cross section of 40 Å2. O2 is different, having a cross section increasing with v. For the vibrational levels v=0–3, it was possible to study the rotational dependence between J’=1.5 and 20.5 for NO as the collider. Over this range, a smooth decrease of about 10% in the quenching rate is observed. [ABSTRACT FROM AUTHOR]