Novel 3-acyloxymethyl-cephem compounds of the formula: <IMAGE> wherein R1 is hydrogen or an acyl group; W is acetonyl, or a group represented by -X-COOH or -X-OH (X is an organic residue) or salts thereof were found to be useful as starting materials for preparing cephalosporins of the formula: <IMAGE> wherein R3 stands for a residue of a nucleophilic compound and R1 has the same meaning as above.
