2-Styrylbenzothiazole (1), 2-styryl (2)- and 2-phenylbenzoxazole (3) reacted with excess chlorosulfonic acid (6 equivalents) to give the sulfonyl chlorides (8, 14, 20). The pure sulfonyl chlorides were not isolated and were characterised by conversion into 14 sulfonamides (9–13, 15–19, 21–24) the hydrazide (25) and acetone hydrazone (26). 2-Styrylbenzothiazole (1) by heating with a larger amount of chlorosulfonic acid (12 equivalents) afforded a chlorinated bis-sulfonyl chloride (27), which was characterised by formation of the bis-morpholidate (28). The NMR and MS spectral data are briefly discussed.