To provide a method for electrochemical methoxylation of a methine, methylene or methyl group of aliphatic or alicyclic mono-ether or di-ether.

The electrochemical methoxylation of a methine, methylene or methyl group present at α-position with respect to an ether-oxygen atom is conducted in an electrolytic cell, which has a solid electrolyte comprising a cation exchange membrane or several cation exchange membranes layered in the up-and-down direction and has a cathode and an anode which are brought into contact directly with the solid electrolyte, using, as an electrolytic solution, an organic solution containing, by weight, a) 10-90% methanol, b) 1-50% compound selected from starting ethers or methoxylated ethers and c) 0-30% other inert solvent and substantially containing no supporting electrolyte.