Disclosed are antibiotic 3-(substituted thio)-7-(substituted methyl) cephalosporins, derivatives and analogues thereof; wherein the methyl substituent is, inter alia, hydroxyl, ketonic oxygen, imino nitrogen, amino or mercapto. Also disclosed are processes for the preparation of such compounds and their pharmaceutically acceptable salt, ester and amide derivatives; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.