The starting material 1,2,4-triazole derivative (3) was used to synthesize some novel condensed triazoles. Thus, treatment of compound (3) with phenyl isocyanate in refluxing pyridine furnished the novel [1,2,4]triazolo[4,3-b][1,2,4]triazole derivative (5). Also, cyclization of compound (3) with phenyl isothiocyanate afforded the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivative (7). Hydrazone derivative (9d) was allowed to react with some halogenated reagents such as chloroacetone, ethyl chloroacetate, and chloroacetonitrile to furnish thiazole derivatives (12), (13), and (15), respectively. In a similar manner, bishydrazone (17) was used to prepare the novel bisthiazoles (18) and (19). Some of the synthesized compounds were evaluated for their antibacterial activity. [ABSTRACT FROM AUTHOR]