Abstract: Process for the liquid phase epitaxial deposition on a substrate of a ternary compound crystallizing in the same system as the substrate and complying with formula A.sub.x B.sub.n-x C.sub.m in which A, B and C are elements of the periodic classification of elements, n and m are integers, which can be the same or different, and x is between O and n, wherein said process comprises:(a) preparing an epitaxy bath by raising one of the elements A or B of the ternary compound and a stoichiometric solid binary compound of the two other elements of the ternary compound to a temperature such that there is formed with an excess of the said binary compound in the solid state, a liquid phase whose composition corresponds to the equilibrium with the solid phase A.sub.x B.sub.n-x C.sub.m,(b )contacting the bath with the substrate to be coated, and(c) depositing thereon, the ternary compound A.sub.x B.sub.n-x C.sub.m.