A series of thiadiazole derivatives were synthesized with differently substituted benzoic acids which were cyclized to give differently substituted thiazolidin-4-one. Elemental analysis, IR, $^1H$ NMR, $^{13}C$ NMR and mass spectral data confirmed the structure of the newly synthesized compounds. The derivatives of these moieties were evaluated for antimicrobial activity. Most of the synthesized compounds showed good antimicrobial activity at 200 and $100;{mu}g/mL$. Compounds showed most significant antibacterial activity against gram negative test organism Escherichia coli and most significant antifungal activity against test organisms Aspergillus niger and Candida albicans. It was observed that compounds with $OCH_3$ at 3, 4 position of phenyl ring [5(a-l)] were more potent against microbes as compared to compounds having unsubstituted phenyl ring [4(a-l)].