A cephalosporin compound of the formula (I):
wherein X and Y may be the same or different and are a hydrogen or halogen atom; Z is a hydrogen or halogen atom, -CH=CH₂, -CH=CH-CH₃, -OR¹, -SR² or -CH₂W in which R¹ and R² are a lower alkyl group and W is a hydrogen atom or a nucleophilic residue, its pharmaceutically acceptable salt, a process for preparing the same and their antibacterial composition.
Cephalosporin compounds of the formula (I): ##STR1## wherein R.sup.1 and R.sup.2 may be the same or different and are a hydrogen atom or a lower alkyl group of 1-5 carbon atoms and A is a hydrogen atom or a nucleophilic compound residue or pharmacologically acceptable salts thereof have excellent antibacterial activity against Gram positive and Gram negative microorganisms.