A compound of the formula: ##STR1## wherein R.sup.1 stands for a halogenoethoxycarbonylamino and R.sup.2 stands for hydrogen or a halogen, is an important intermediate for producing a cephalosporin derivative of the formula: ##STR2## wherein R.sup.3 stands for methyl, acetoxymethyl, carbamoyloxymethyl, an alkoxymethyl, an alkylthiomethyl, 2-carboxy-1-ethenyl, or a heterocyclic thiomethyl, R.sup.5 stands for hydrogen or methoxy and R.sup.2 has the same meaning as defined before, which is active against various pathogenic microorganisms even at a low concentration.
A compound of the formula: ##STR1## wherein R.sup.2 is hydrogen or a halogen and R.sup.3 stands for methyl, acetoxymethyl, carbamoyloxymethyl, an alkoxymethyl, an alkylthiomethyl, 2-carboxy-1-ethenyl, or a heterocyclic thiomethyl, or a pharmaceutically acceptable salt thereof, is found to have a broad antimicrobial spectrum and, in particular, effective against Gram-negative bacteria including Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescense as well as Gram-positive ones including antibiotic resistant strains. Thus, these compounds may be used for antimicrobial agents in therapeutical purposes.