Gas-phase FeO + can convert benzene to phenol under thermal conditions. Two key intermediates of this reaction are the [HO-Fe-C 6 H 5 ] + insertion intermediate and Fe + (C 6 H 5 OH) exit channel complex. These intermediates are selectively formed by reaction of laser ablated Fe + with specific organic precursors and are cooled in a supersonic expansion. Vibrational spectra of the sextet and quartet states of the intermediates in the O–H stretching region are measured by infrared multiphoton dissociation (IRMPD). For Fe + (C 6 H 5 OH), the O–H stretch is observed at 3598 cm −1 . Photodissociation primarily produces Fe + + C 6 H 5 OH; Fe + (C 6 H 4 ) + H 2 O is also observed. IRMPD of [HO-Fe-C 6 H 5 ] + mainly produces FeOH + + C 6 H 5 and the O–H stretch spectrum consists of a peak at ∼3700 cm −1 with a shoulder at ∼3670 cm −1 . Analysis of the experimental results is aided by comparison with hybrid density functional theory computed frequencies. Also, an improved potential energy surface for the FeO + + C 6 H 6 reaction is developed based on CBS-QB3 calculations for the reactants, intermediates, transition states, and products.