The quinoxalinone skeleton is used as an intermediate in designing novel quinoxalinone derivatives with potential as novel anticancer, antimicrobial, antifungal, antithrombotic and antianxiolytic agents and glycogen phosphorlyase inhibitors, and also as fluoroionophores. The present paper describes the synthesis and antibacterial activity of some novel 3,4-dihydroquinoxalin-2H-(1H)-one derivatives 5a-5j (Scheme 1) from commercially available 1,2- phenylenediamine as starting material. The newly synthesized compounds were screened to evaluate their antibacterial activity. Most of the compounds were found to display good to moderate antibacterial activity against all the tested bacterial strains. It was observed that among all the compounds tested, compound 5i exhibited equipotent activity and 5j showed good activity (having fluorine substituent) against all the tested bacterial strains and the remaining compounds such as compounds 5a, 5b, 5c, 5d and 5e having methyl and methoxy substituents displayed moderate activity while the compounds 5f, 5g and 5h showed no activity.