Synthesis of new 1,2,4-tri and 1,3,4-thiadiazoles, bearing isomeric pyridyl and 1-naphthyl is reported using 1,4-disubstituted thiosemicarbazides in alkaline and acidic media respectively. The methylthio and benzylthio derivatives of the synthesized triazoles are also reported. All of the synthesized compounds Were characterized by their FT-IR. H-1-NMR and mass spectral data. The antibacterial studies of Some of the synthesized compounds against S. aureus and E. coli, its MIC values are reported. None of them have important antibacterial activities.