Using high resolution spectrograms, the broadened linewidths for several bands of the B ² Sigma ⁺-A ² Sigma ⁺ system of OD have been reinvestigated. Comparison between observed and calculated halfwidths shows that the high-vibrational level predissociation is a case c⁺ one, due to a first order spin orbit interaction, with a repulsive ⁴ Pi state which crosses the A ² Sigma ⁺ state of OD at r=1.65 AA between v=7 and v=8, and between v=5 and v=6 for OH. The vibration- rotation interaction is shown to be responsible for the strong halfwidth dependence on the rotational quantum number.