Novel N-formyl hydroxylamine compounds (I) and their derivatives are disclosed. These N-formyl hydroxylamine compounds inhibit peptidyl deformylase (PDF), an enzyme present in prokaryotes . The compounds are useful as antimicrobials and antibiotics. The compounds of the invention display selective inhibition of peptidyl deformylase versus other metalloproteinases such as MMPs. Methods of preparation and use of the compounds are also disclosed. wherein R1 is hydrogen, alkyl, heteroalkyi, heterocycloalkyl, aryl or heteroaryl.; R3 is hydrogen, halogen, or alkoxy; R4 is aryl, or heteroaryl; or n is 0 to 3 and provided that R1 is cycloalkyl and/or R4 is an optionally substituted 6 membered, monocyclic heteroaryl ring having 2, 3 or 4 nitrogen heteroatoms in the ring wherein one or more of the ring nitrogen heteroatoms is optionally oxidized.