A 2-D coordination polymer, {[Cd4(ppmh)4(fum)4(H2O)4].3H2O}n (CP) (H2fum, fumaric acid; ppmh, N-Pyridin-2-yl-N′-pyridin-4-ylmethylene-hydrazine) has been synthesized and structurally characterized by single-crystal X-Ray diffraction study. The structure shows that the coordination polymer is constituted by fumarato bridging via chelation/bidentate coordination to neighbouring Cd(II) centers. The ligand, ppmh has two terminal pyridyl-N and hydrazino-N binding centers. One of the pyridyl-N and hydrazino-N forms a five-member chelate ring with Cd(II) while other pyridyl-N coordinates to adjacent Cd(II) ion. The 2D CP extended itself to 3D supramolecular array by virtue of π--- π interaction and H-bonding. The optical bandgap of the CP is 3.29 eV which implies semiconducting nature and has been supported by the ground state computational analysis. The electrical conductivity and I-V characteristic have shown that the conductivity is improved upon light irradiation (DC conductivity: dark, 0.87 × 10−3 and light, 2.45 × 10−3 Sm−1) and approves the Schottky Barrier Diode (SBD) feature. The DFT computation and the partial density of states (PDOS) calculation show that the π-character of the aromatic hydrazone ligand dominates the valence and conduction bands with negligible participation of the Cd orbitals.