The defect structure of lithiated tin- and titanium-doped α-Fe 2 O 3 has been assessed using interatomic potential calculations. Of the models considered for lithiation, a model in which Li + occupies an interstitial site balanced by the reduction of Fe 3 + to Fe 2 + on an Fe 3 + site was found to be more favourable than the substitution of Li + on an Fe 3 + octahedral site balanced by an O 2 - vacancy. Insertion of lithium into the interstitial site between two adjacent M 4 + ions was particularly favourable. The calculated lattice parameters decrease on lithiation as has been observed experimentally.