Acylation of 3,5-diamino-1,2,4-triazole with anhydrides and chlorides of alkane-and arenecarboxylic acids and arenesulfonyl chlorides in aqueous solutions and under phase-transfer catalysis was studied.Acyl, aroyl, and arenesulfonyl derivatives of 3,5-diamino-1,2,4-triazoles are used as intermediates for preparing nitro and azido derivatives of 1,2,4-triazoles [133], and also drugs and herbicides [4 37]. The most general route to acyl derivatives of 3,5-diamino-1,2,4-triazole is acylation of 3,5-diamino-1,2,4-triazole I, which can yield mono-, di-, and triacetyl derivatives depending on the reaction conditions [1, 4, 83 10]. However, triazole I is expensive, despite the fact that it is prepared from available substances: dicyanodiamide II and hydrazine [11]. The high cost of I is due to its difficult isolation from reaction mixtures. Our previous studies [12,13] showed that some derivatives of I can be prepared from dicyanodiamide and hydrazine without isolation of I.In this study we developed a procedure for preparing 1-acyl-, 1-aroyl-, and 1-arenesulfonyl-3,5-diamino-1,2,4-triazoles by acylation of products of the reaction of nitrile II with hydrazine without isolation of I: