The gas phase fragmentation reactions of η² coordinated aldehydes in [VO₂(η²-OCHR)]⁻, which have previously been shown to play a role in the catalytic oxidation of alcohols to aldehydes, were examined using a combination of isotope labelling experiments and collision induced dissociation in a quadrupole ion trap mass spectrometer. The experimental data were interpreted with the aid of density functional theory calculations (DFT). The types of fragmentation reactions observed depend on the nature of the R group. When R = H, the dominant fragmentation channel involves formation of [VO₂H₂]⁻via loss of CO. Minor losses of H₂ and CH₂O are also observed. When R = Me, loss of H₂ is observed to give rise to an ion at m/z 125 corresponding to the formula [V, O₃, C₂, H₂]⁻. DFT calculations on the [VO₂(η²-OCHR)]⁻ and their CID reaction products have identified minimum energy structures for all reactants and products involved. DFT calculations also provided insights into key intermediates on the potential energy surface associated with these fragmentation reactions, including: [(H₂)VO₂(CO)]⁻ in the case of R = H; and [HVO₂(η¹-OCHCH₂)]⁻ in the case of R = Me. The results presented provide insights into potential side reactions occurring during catalysis of alcohols over vanadium oxides, for instance, the over-oxidation of methanol to carbon monoxide.