The title compound {[Zn(NIT4Py)(fum)(H2O)(2)]center dot H2O}(n), where NIT4Py = 2-(4'-pyridinyl)-4,4,5,5-tetra-methylimidazoline-1-oxyl-3-oxide and fum = fumarate, has been prepared and structurally characterized by X-ray diffraction. It crystallizes in triclinic, space group P (1) over bar with a = 6.9533(9), b = 9.805(1), c = 15.248(2) angstrom, alpha = 94.608(2), beta = 92.328(2), gamma = 105.840(2)degrees, C16H24N3O9Zn, M-r = 467.75, V = 994.8(2) angstrom(3), Z = 2, D-c = 1.562 g/cm(3), mu(MoK alpha) 1.289 mm(-1), F(000) = 486, the final R = 0.0243 and wR = 0.0622 for 3505 independent reflections with R-int = 0.0125. The Zn(II) adopts a distorted five-coordinate triangle bipyramidal geometry. The basic framework structure of the complex is a 1-D chain. The intrachain hydrogen bonds are helpful to stabilize the I-D chain structure. Furthermore, the chains are connected by O-H center dot center dot center dot O hydrogen bonds to give a 2-D double-layer network.