A Fe-based coordination polymer, [Fe(C₂O₄)_0.5(4-NCP)]_n·2nH₂O (1, 4-HNCP = 2-(4-carboxy- phenyl)-1H-imidazo(4,5-f)-(1,10)phenanthroline, H₂C₂O₄ = oxalic acid), was hydrothermally synthesized and characterized by infrared spectrum, elemental analysis, single-crystal X-ray diffraction, power X-ray diffraction, and UV-vis absorption spectrum. Structural analyses reveal that polymer 1 possesses a (4, 4)-connected 2D network. In addition, 1 shows photocatalytic activity toward the degradation of rhodamine B (RhB) in the presence of H₂O₂ under visible light illumination.