There is provided cephalosporin derivatives of the formula ##STR1## in which R.sup.1 is carboxy-lower alkyl andR.sup.2 is hydrogen, a cation or (with the oxygen atom) a readily hydrolyzable ether group,as well as readily hydrolyzable esters and salts of these compounds and hydrates of the compounds of formula I and of their esters and salts. Also provided are methods for their manufacture and pharmaceutical preparations containing the compounds of formula I.