A series of new imidazo[2,1-b]thiazoles was prepared in moderate to good yields in a four step synthesis using the TDAE methodology from 6-chloromethyl-5-nitroimidazo[2,1-b]thiazole and keto esters, ketomalonates and ketolactams. All compounds were tested for their antibacterial and antifungal activities against four bacterial strains (two Gram positive and two Gram negative ones) and four yeasts. Among these synthesized 5-nitroimidazo[2,1-b]thiazoles, the compounds 1 and 6 showed potent antimicrobial activities against all candida strains and compound 3e showed an interesting antifungal potential against Candida tropicalis.