- It has been predicted that photodissociation of vibrationally excited HOD may preferentially yield either OD+ H or D+ OH, depending on the vibrational mode and the dissociation wavelength. To date, only the former preference has experimentally been demonstrated. In the present work preferential O–D bond breaking has been achieved from the photolysis of HOD (νOD= 3) at 193 nm. HOD was prepared in a specific rovibrational level of the second overtone of the O–D stretch via infrared excitation. The subsequent photolysis led to enhancement of both OH and OD production, the OH/OD branching ratio being 2.6±0.5. The results agree with the predictions of Imre and co‐workers [J. Phys. Chem. 93, 1840 (1989)] on the enhancement of νOD≥ 3 photodissociation but differ in the branching ratio obtained at the specific photolysis wavelength.