The reaction of vinylhalides with phenylselenenyl chloride in alcohols affords α-alkoxy acetals and diphenyl diselenide which can be oxidized to PhSe cations by nitrate or persulfate anions. The reaction can be carried out with catalytic amounts of PhSeCl or PhSeSePh. The reaction proceeds through the formation of the methoxyselenenylation product which then suffers solvolysis. Under controlled conditions