The energetics of selected dicationic iron oxides and hydroxides FeOmHn2+ (m = 1, 2; n less than or equal to 4) are probed by charge-stripping mass spectrometry in conjunction with ab initio calculations employing the B3LYP/6-311+G* level of theory. Specifically, Fe+, FeO+, FeOH+, Fe(H2O)(+), [Fe,O-2,H-2](+), (H2O)FeOH+, and Fe(H2O)(2+) and their respective dications are examined. In most cases, reasonable agreement between experiment and theory is found, and discrepancies can be attributed to interferences in the experimental study. Nevertheless, some shortcomings of the theoretical approach are obvious. Combination of experimental and theoretical results leads to adiabatic ionization energies of the monocationic iron compounds: IEa(FeO+) = 18.3 +/- 0.4 eV, IEa(FeOH+) = 17.0 +/-0.4 eV: IEa(Fe(H2O)(+)) = 14.3 +/- 0.5 eV, IEa((H2O)FeOH+) = 15.6 +/- 0.5 eV, and IEa(Fe(H2O)(2)(+)) = 12.6 +/- 0.4 eV. In the case of [Fe,O-2,H-2](+), structural isomerism and isobaric interferences give rise to a composite charge-stripping peak and prevent the experimental determination of the ionization energy. Interestingly, the computational results suggest a reversed order of stabilities for the mono- and dicationic [Fe,O-2,H-2](+/2+) isomers, i.e., Fe(OH)(2)(+) > (H2O)FeO+ > Fe(H2O2)(+) versus Fe(H2O2)(2+) > (H2O)FeO2+ > Fe(OH)(2)(2+). The ion energetics are used to assess the effects of ligation on the stabilities of the iron dications. While the covalent Fe-O and Fe-OH bonds decrease with increasing oxidation state of the metal, the interactions with water are dominated by electrostatic contributions. On average, solvation by water lowers the second ionization energy of the iron compounds studied by as much as 1.6 +/- 0.3 eV.