Cephalosporin compounds of the formula:
wherein R1 is amino or protected amino; R2 is substituted or unsubstituted heterocyclic group having 1 - 3 hetero atoms selected from oxygen and sulphur; R3 is carboxyl or protected carboxyl; R4 is nucleophilic compound residue; R5 is carboxyl, protected carboxyl and -COO-, a pharmaceutically acceptable salt thereof and their synthetic intermediate of the formula:wherein R11 is amino or protected amino; R2 is substituted or unsubstituted heterocyclic group having 1 - 3 hetero atoms selected from oxygen and sulfur; R3 is carboxyl or protected carboxyl; -COOY is carboxyl or protected carboxyl. Said cephalosporin compound is useful as antibacterial agent.