High-resolution cavity ring-down spectroscopy has been used to record three vibronic bands of the transition of room-temperature formyl chloride (HClCO). These three bands A 3 1AAÈX 3 1A@ (p* ^nO ) (6 0 1 , 5 0 1 6 0 1 and are all vibronically induced through the activity of the out-of-plane inversion vibration and 2 0 1 5 0 1 6 0 1) l 6 , are found to obey type-a selection rules. Rotational constants have been derived from the analysis of these bands and used to give information on the geometrical structure of the excited state. The properties of the A 3 state are found to be intermediate between those of the corresponding states of formaldehyde and formyl Ñuoride.