A mild, general, convenient, and efficient one-pot synthesis of 2-phenyl-5-substituted-1, 3, 4- oxadiazoles is described. Both (hetero) aryl and alkyl carboxylic acids were efficiently condensed with benzohydrazide in the presence of TBTU to give diacylhydrazine intermediates. The latter underwent a smooth TsCl-mediated cyclodehydration reaction to afford 2-phenyl-5-substituted-1, 3, 4-oxadiazoles in good to very good yields.