A 3D nickel-organic framework formulated as {[Ni-2(fum)(2)(bpt)(2)(H2O)]center dot 3H(2)O}(n) (1), built from a mixed fumaric ion (fum), 1H-3,5-bis(4-pyridyl)-1,2,4-triazole (bpt), and nickel salt, has been hydrothermally synthesized and characterized. Compound 1, having a Ni-fum chain structure in which the chains are pillared by the bpt spacers in a 3D "brick-wall"-like architecture, exhibits canted antiferromagnetism at 5.0 K. Below this temperature, slow relaxation is observed from the alternating-current susceptibility measurements corresponding to the spin-glass-like behavior.