Thiophene derivatives of the formula ##STR1## IN WHICH R.sub.x is --S--CHR.sub.5 --CONHOH or --S--CHR.sub.5 -5-tetrazolyl in which R.sub.5 is H or alkyl of 1-6 carbon atoms and R.sub.y is 0-2 of alkyl or alkoxy of 1-6 carbon atoms or halogen, and their pharmacologically acceptable salts with bases, possess antilipolytic activity.