A library of novel 4-[4-(4-nitrophenoxy)phenyl]-5-substituted-2H-1,2,4-triazole-3-thiones containing different substituents at the 5-position is synthesized. The mechanochemical treatment is followed to synthesize target compounds 8 (ap), and the yields are compared by both the grinding method and the conventional method. The structure of the intermediate, isothiocyanato-4-(4-nitrophenoxy)benzene 6, is analyzed by single crystal X-ray studies. The title compounds are characterized by spectral and elemental analyses and further evaluated for their efficacy as anthelmintics in vitro. Compounds 8c, 8j, 8k, 8l, and 8m exhibit significant anthelmintic activity.