A method has been found for the synthesis of fluoride-containing alpha-hydrothionyl fluorides by heating polyfluoroalkenyl benzyl sulfides having fluoride atoms in the alpha-position relative to the sulfur atom with fluorosulfonic acid. The reactions of the acid fluorides obtained with secondary amines were studied. The reaction of the alpha-hydrotetrafluorothiopropionyl fluoride with NH(Me)2 leads to the amide of the corresponding acid, while the product of alpha-hydrohexafluorothioisobutyryl fluoride with diethylamine is the dimer of bis(trifluoromethyl) thioketene.