The review addresses and highlights the main results of research on the physicohemical properties of single-phase and composite materials based on transition metal oxides in relation to their practical application as electrode materials for symmetrical solid oxide fuel cells. The electronic structures and thermodynamic stability of transition metal oxides with the perovskite structure are discussed. A detailed consideration is given to the thermal behaviour, chemical stability, electrical conductivity and electrochemical properties of a broad range of electrode materials based on iron-, chromium- and manganese-containing perovskite-like oxides and oxides that crystallize in other structure types. The analysis revealed the most promising compositions of electrode materials for symmetrical solid oxide fuel cells and effective approaches to the improvement of their functional characteristics. The bibliography includes 202 references.

Arrhenius plots of the total conductivity in (1 and 3) dry and (2 and 4) wet air of two Yb ₆ MoO ₁₂ polymorphs: (1 and 2) bixbyite ( Ia 3̄(206)) Yb ₆ MoO ₁₂ and (3 and 4) rhombohedral ( R 3̄) Yb ₆ MoO ₁₂ ; Yb ₆ MoO ₁₂ rhombohedral ( R 3̄) → Yb ₆ MoO ₁₂ bixbyite ( Ia 3̄(206)) at T ∼ 1600 °C.

The tolerance factor is a good criterion to understand the structural transitions in Ln_2−xCa_xScMO_7−δ (M = Nb, Ta).