Several 6-aryloxymethyl-2,4-dimethyl-1,2,4-triazolo [3,4-b]-1,3,4- thiadiazepines II and 2-arylamino-4-aryloxymethyl-1,2,4-triazolo [3,4-b][1,3,4] thiadiazoles III have been synthesized from the synthon 3-aryloxymethyl-4-amino- 5-mercapto-1,2,4-triazoles I. The molluscicidal activity of few titled compounds have been evaluated against the snail Lymnaea acuminata. The LC50 slope, t-ratio, heterogeneity and g values have been determined and discussed.