2-(phenyl seleno) ethanoicacid (1) and 3-(phenyl seleno) propanoicacid (2) has been synthesized in more economical and efficient method using phase transfer catalyst, tetraethylammonium bromide. Compound 1 & 2, has been synthesised by reacting nucleophile, PhSe- (generated insitu by borohydride reduction of Ph2Se2) with ?-chloro aceticacid & 3-chloro propanoicacid via phase transfer catalysis. The presence of catalyst improves the yield of the products and lowers the reaction time, however in absence of the catalyst yield was very poor. Elemental analysis, IR, 1H, 13C, 1H-1H COSY NMR, ESI mass and molar conductance data has been used to authenticate the new species. The antimicrobial evaluation of both the compounds indicates their significant activity at different concentrations against selected bacterial and fungal strains. These Compound bear an acidic group, showed higher activities due to increase in the lipophilicity and easier penetration of the compounds into the outer cell wall of the microorganisms, which causes death due to cell membrane rupturing thereby boosting the bioactivity of these compounds.