A new Schiff base ligand, pyridine 3-carbaldehye thiosemicarbazone (1), was synthesized and structurally characterized. Its synthesis involves a Schiffbase condensation of thiosemicarbazide and pyridine 3-carbaldehyde. The new compound was determined through elemental analyses, FT-IR spectroscopy, and single-crystal X-ray crystallography. Compound 1 has a monoclinic crystallographic system with a P21/n space group. It can be introduced as a tridentate NNS donor ligand for the synthesis of several complexes with new structures. With several H-bonding, the structure showed the three-dimensional structures.Inaddition, the electronic properties of pyridine 3-carbaldehyde thiosemicarbazone are studied, in atomic-scale,using density functional theory (DFT) at and quantum theory of atoms in molecules (QTAIM). Also, the external electric field (EF) effects on electronic/vibrationalpropertiescharacteristics of this molecular system (as molecular wire) are studied, using QTAIM, at theatomic scale (EF-QTAIM).Moreover, analysis of the current-voltage (I-V) curve results showed that this molecule can be used as a stable molecular wire.