A series of novel 4-aryl/chloroalkyl-2-(2,3,5-trichlorophenyl)-1,3-thiazoles (5a-g and 7a-e) were synthesized by condensing 2,3,5-trichlorobenzenecarbothioamide with phenacyl bromide/dichloroacetone. 2,3,5-Trichlorobenzaldehyde thiosemicarbazone on treatment with phenacyl bromide afforded 4-aryl-2-(2,3,5-trichlorophenylidenehydrazino)-1,3-thiazoles (10a-g) in good yield. The newly synthesized compounds are characterized by IR, (1)H NMR and mass spectral studies. These compounds were also screened for their antibacterial and antifungal activities. Preliminary results reveal that some of the synthesized compounds are showing promising antimicrobial activity.