One-stage synthesis of 5-substituted (alkyl, aryl, heteroaryl, arylalkyl, heteroalkyl, alkoxy-, aryloxy)-2-(2,4-dihydroxyphenyl)-1,3,4-thiadiazoles is described. The compounds were prepared by the reaction of sulfinyl-bis(2,4-dihydroxythiobenzoyl) (STB) with hydrazides or carbazates. The structure of new compounds was assigned by ir, nmr and ms data.