An approach for estimating at the DFT level of the standard redox potentials of the inclusion compounds based on Fe(III) and Fe(II) aqua complexes inside the cavities of cucurbit[n]urils (n = 6-8) has been proposed. These inclusion compounds were established to have compositions which can be described by the formulas [Fe(H2O)(6)](3+/2+)@gCB[6] and [Fe(H2O)(6)center dot 4H(2)O](3+/2+)@CB[7,8]. Redox potentials E-0 relative to the standard hydrogen electrode for the half-reaction Fe(III)/Fe(II) in the CB[n] cavities calculated at the PBE/TZVP level within the molecular continuum solvation model are 1.607, 0.949, and 0.847 V for n = 6, 7, and 8, respectively. The obtained values indicate a relative increase of the oxidative ability of Fe(III) aqua-ions in the cavities of the examined CB[n], especially in CB[6], compared to the calculated value (E-0 = 0.786 V) for the same half-reaction in the bulk of aqueous solution. Possible causes of the detected trend are discussed. The calculations also showed that the Fe(III) aqua complex inside the CB[6] changes its magnetic properties, transforming into a low-spin state with a total spin S = 1/2, whereas for all other systems high spin states in accord with the classical ligand field theory are realized.