The Z-sclective formation of alpha-fluoro-alpha,beta-unsaturated esters was achieved using the deselenenic acid of the synand/or anti-3-aryl-2-fluoro-3-hydroxy-2-organoselanylacetates 3 and 4 with trifluoromethanesuffonic acid. In contrast, the 3-alkyl-substituted propanoates 3f and 4b stereospecifically underwent alkenylation to give the (E)- or (Z)-alpha-fluoro-alpha,beta-unstaurated esters 5f. We were also successful in the one-pot alkenylation reactions.