The reactions of 5-chloro-2-thiophenesulfonyl chloride are described. Treatment of the sulfonyl chloride with ammonia, hydrazine hydrate, sodium azide, indole and imidazole gave the sulfonamides (5), sulfonohydrazide (4), sulfonyl azide (3), 1-(5-chloro-2-thiophenesulfonyl)indole (27) and 1-(5-chloro-2-thiophenesulfonyl)-imidazole (26), respectively. The sulfonyl chloride was reacted further with 20 aryl-and cycloalkyl-amines to give the corresponding sulfonamides (6)-(25). Attempted chlorination of the sulfonyl chloride (2) with sulfuryl chloride or bromination of the sulfonyl azide (3) with pyridinium bromide perbromide failed. However, nitration of the sulfonyl chloride (2) with fuming nitric acid gave the 4-nitro-sulfonyl chloride (28), which with sodium azide afforded the 5-chloro-4-nitro-sulfonyl azide (29). The sulfonyl azides, (3) and (29), have been reacted with triphenylphosphine, triethylphosphite, norbornene and cyclohexene. The azides reacted further with indole and 1-methylindole to give the 2-sulfonyl-iminoindolines (34)-(36). The infra-red spectra and mass spectra of some of the substituted thiophenesulfonyl derivatives are discussed.