Abstract New methods for the synthesis of 1, 3, 4-oxadiazole and 1, 3, 4-thiadiazole have been described. No cyclizations took place in the absence of ZnCl 2. 1, 3, 4-Thiadiazoles are formed in the presence of ZnCl 2 alone, whereas oxadiazoles are produced when a base such as Et 3 N or KOH was used along with ZnCl 2.% Yields are optimized.