The invention relates to novel cephem compounds, of high antimicrobial activity, of the formula ##STR1## wherein R.sup.1 is amino or protected amino,R.sup.2 is lower alkyl substituted with 1 to 3 halogen atoms,R.sup.3 is thiadiazolylthiomethyl which may be substituted with lower alkyl, or tetrazolylthiomethyl which may be substituted with lower alkyl or lower alkenyl, andR.sup.4 is carboxy or protected carboxy, and a pharmaceutically acceptable salt thereof.