Method of depositing a buffer layer of epitaxial metal oxide on a functionalised surface of a textured metal substrate, said method comprising the following steps: (1) a layer is deposited of a precursor of an oxide of the type A2−xB2+xO7 where A represents a metal of valency 3 or a mixture of several of these metals, and B a metal of valency 4, and x is a number between −0.1 and +0.1, from a solution of carboxylates of said metals A and B, (2) said layer of oxide precursor is left to dry, (3) heat treatment is carried out in order to pyrolyse said oxide precursor and to form the oxide, at least part of said heat treatment being carried out under a flow of reducing gas.