The title compound, C(11)H(9)N(5)O(2)S, was synthesized from N-phthaloylglycine and thio-carbohydrazide by the fusion method. This is the first report of a triazole derivative of N-phthaloylglycine. The title compound exists in the thione form. The mol-ecule is non-planar, with a dihedral angle between the isoindoline ring system and the triazole ring system of 82.24 (5)°. The crystal structure is stabilized by inter-molecular hydrogen bonding linking the mol-ecules into a three-dimensional network.