A series of thioether derivatives of 2-Chloro-3-methylquinoxaline have been synthesized by reacting 3- methylquinoxalin-2-thiosodium with 2-chloro-N-(substituted aryl/alkyl)-acetamides. The synthesis was initiated with the reaction of o-phenylenediamine (1) with ethyl pyruvate in n-butanol to yield 2-hydroxy-3-methyl quinoxaline (2), which on treatment with POCl3 ,yielded 2-chloro-3-methylquinoxaline(3).A mixture of the compound(3) and sodium sulphide in DMF was refluxed to yield 3-methylquinoxalin-2-thiosodium(4),which on treatment with different Nsubstituted chloroacetamides afforded the one pot synthesis of 2-(2-methylquinoxalin-3-ylthio)-N-substitutedaryl/ alkyl)-acetamides(5a-k). 2-chloro-N-substituted acetamides were prepared by treating substituted anilines in glacial acetic acid with chloroacetylchloride, warming on the water bath for half an hour and then precipitating, 2- chloro-N-substituted acetamides by addition of saturated aqueous solution of anhydrous sodium acetate. A compound 2-(benzylthio)-3-methylquinoxaline 5l was also prepared. The newly synthesized compounds have been characterized by IR, and 1HNMR spectra, analysis. All compounds (5a-l) were screened for their in vivo anti inflammatory activity by carrageenan induced rat paw edema method. Compounds 5a, 5b, 5d, 5e, 5g and 5k have been found to possess good anti inflammatory activity.