A series of synthetic aliphatic and aromatic nitro derivatives with antimicrobial activity were studied by reversed Phase — high performance liquid chromatography using spherosorb 5 OD S PU Column RPC18 ). A wide range of retention times were obtained. The ceacity factor for the majority of these compounds were K > 1 which means they are resolable under conditions used (Methanol/ Water)(50:50) V/V) at 25c and flow rate was 1 ml / nun in every run.