2-R-5-R'-s-Triazolo[3, 4-b]-1, 3, 4-thiadiazoles (V) were synthesized starting with 2-hydrazino-5-R-1, 3, 4-thiadiazole (III : R=CH₃, C₂H₅, n-C₃H₇, iso-C₄H₉, C₆H₅), reacting them with either ethyl orthoacylate or ethyl acylimidate (R'=H, CH₃, C₂H₅, n-C₃H₇, n-C₄H₉) to form ethyl N'-(5-R-1, 3, 4-thiadiazol-2-yl) hydrazonoacylate (IV), and cyclization with acetic acid. Treatment of (III) by heating with 80% formic acid produced 2-R-s-triazolo[3, 4-b]-1, 3, 4-thiadiazole (V, R'=H).