NOVELTY - The preparation of a layer of metal oxide on a substrate consists of : dispersion of a metal oxide powder in a liquid medium incorporating a dispersion solvent and a dispersing agent, this liquid medium not containing any plastifying agent or binder, to form a suspension A of the powder in the medium; adding to the suspension A, a solution of at least one polymer in a solvent, to obtain a suspension B.    USE - The invention is used for the preparation of metal oxide layers on substrates, notably for thin films on dense or porous substrate of metal, ceramic or glass. It is particularly applicable for the deposition of dense electrolyte and cathode layers, of the mixed oxide type, in Solid Oxide Fuel Cells (SOFC).    ADVANTAGE - The invention provides a method for the preparation of metal oxide layers on a substrate that does not require any pre-treatment of the substrate and allows the deposition, in a single stage, of metal oxide layers with a thickness in the range of 1 to 10 microns. It ensures that porous substrates can be coated without any difficulty. It provides greater flexibility than conventional tape casting methods and assures the deposition of excellent quality layers on substrates with a large surface area and/or with complex geometry. It assures strong adherence of the layer on the substrate after calcination and can be applied to a wide range of oxides.    DETAILED DESCRIPTION - The preparation of a layer of metal oxide on a substrate consists of:    (a) dispersion of a metal oxide powder in a liquid medium incorporating a dispersion solvent and a dispersing agent, this liquid medium not containing any plastifying agent or binder, to form a suspension A of the powder in the medium;    (b) adding to the suspension A, a solution of at least one polymer in a solvent, to obtain a suspension B;    (c) depositing the suspension B on the substrate by a dip coating process to obtain a raw layer;    (d) drying the raw layer;    (e) calcining the dried layer.    DESCRIPTION OF DRAWING(S) - The drawing is a graph showing the evolution of the thickness (e, in microns) of layers of YSZ prepared by the inventive method as a function of the ratio (rm) of the suspensions.