Abstract: Novel oximes of the syn isomers of 7-(2-amino-4-thiazolyl)-acetamido-cephalosporanic acid of the formula ##STR1## wherein R is selected from the group consisting of hydrogen, chlorine, methoxy, alkyl and alkylthio of 1 to 5 carbon atoms, cycloalkyl of 3 to 5 carbon atoms, acetoxymethyl, carbamoyloxymethyl, ##STR2## A1K is 1 to 4 carbon atoms, azidomethyl and --CH.sub.2 --S--R' and R' is selected from the group consisting of a nitrogen heterocycle optionally substituted, acyl of an alkanoic acid of 2 to 4 carbon atoms, 2-oxo-(3H)-thiazolin-4-yl-carbonyl and 3-methyl-1,2-oxazol-5-ylcarbonyl, n is an integer from 2 to 4, R.sub.1, R.sub.2 and R.sub.3 are individually alkyl of 1 to 4 carbon atoms or together taken with the nitrogen atom they are attached to form a group selected from the group consisting of 1,4-diazobicyclo (2,2,2)octan-1-ylium and 1,3,5,7-tetraazatricyclo(3,3,1,1.sup.