The experimental and theoretical thermochemistry of the gaseous neutral and ionic iron oxides and hydroxides FeO, FeOH, FeO2, OFeOH, and Fe(OH)(2) and of the related cationic water complexes Fe(H2O)(+), (H2O)FeOH+, and Fe(H2O)(2)(+) is analyzed comprehensively. A combination of data for the neutral species with those of the gaseous ions in conjunction with some additional measurements provides a refined and internally consistent compilation of thermochemical data for the neutral and ionic species. In terms of heats of formation at 0 K, the best estimates for the gaseous, mononuclear FeOmHn-/0/+/2+ species with m = 1, 2 and n = 0-4 are Delta H-f(FeO-) = (108 +/- 6) kJ/mol, Delta H-f(FeO) = (252 +/- 6) kJ/mol, Delta H-f(FeO+) = (1088 +/- 6) kJ/mol, Delta H-f(FeOH) = (129 +/- 15) kJ/mol, Delta H-f(FeOH+) = (870 +/- 15) kJ/mol, Delta H-f(FeO2-) = (-161 +/- 13) kJ/mol, Delta H-f(FeO2) = (67 +/- 12) kJ/mol, Delta H-f(FeO2+) = (1062 +/- 25) kJ/mol, Delta H-f(OFeOH) = (-84 +/- 17) kJ/mol, Delta H-f(OFeOH+) = (852 +/- 23) kJ/mol, Delta H-f(Fe(OH)(2)(-)) -431 kJ/mol, Delta H-f(Fe(OH)(2)) = (-322 +/- 2) kJ/mol, and Delta H-f(Fe(OH)(2)(+)) = (561 +/- 10) kJ/mol for the iron oxides and hydroxides as well as Delta H-f(Fe(H2O)(+)) = (809 +/- 5) kJ/mol, Delta H-f((H2O)FeOH+) = 405 kJ/mol, and Delta H-f(Fe(H2O)(2)(+)) = (406 +/- 6) kJ/mol for the cationic water complexes. In addition, charge-stripping data for several of several-iron-containing cations are re-evaluated due to changes in the calibration scheme which lead to Delta H-f(FeO2+) = (2795 +/- 28) kJ/mol, Delta H-f(FeOH2+) = (2447 +/- 30) kJ/mol, Delta H-f(Fe(H2O)(2)(+)) = (2129 +/- 29) kJ/mol, Delta H-f((H2O)FeOH2+) = 1864 kJ/mol, and Delta H-f(Fe(H2O)(2)(2+)) = (1570 +/- 29) kJ/mol, respectively. The present compilation thus provides an almost complete picture of the redox chemistry of mononuclear iron oxides and hydroxides in the gas phase, which serves as a foundation for further experimental studies and may be used as a benchmark database for theoretical studies.