Novel 3-vinyl-cephalosporins of the formula ##STR1## in which n is 0 or 1, R.sub.1 is hydrogen, a radical of the formula ##STR2## [in which R.sub.4 is hydrogen or a protective radical and R.sub.5 is hydrogen, alkyl, vinyl or cyanomethyl or is a protective radical], or a protective radical, and R.sub.2 is hydrogen, a protective radical or an enzymatically removable radical, or R.sub.1 is hydrogen or an acyl radical which may carry various substituents and R.sub.2 is hydrogen or a protective radical, and R.sub.3 is a radical of the general formula R'.sub.3 --SO.sub.2 --O-- or R".sub.3 --CO--O--, in which R'.sub.3 is alkyl, trifluoromethyl, trichloromethyl or phenyl which is substituted by a halogen atom or by an alkyl or nitro radical, and R".sub.3 is defined like R'.sub.3 or represents methyl which is substituted by acyl or alkoxycarbonyl, or represents ethyl or propyl substituted in the 2-position by acyl or alkoxycarbonyl. These compounds are useful as intermediates for the preparation of antibiotic 3-thiovinyl-cephalosporins.