In the title centrosymmetric mononuclear Ni-II compound, [Ni(C8H5O3)(2)(C10H14N2O)(2)(H2O)(2)], the central Ni-II atom is coordinated by two O atoms from two 4-formylbenzoate (FOB) ligands, two O atoms from two water molecules and two N atoms from two diethylnicotinamide (DENA) ligands. The coordination geometry is slightly distorted octahedral, with four O atoms in the equatorial plane and two N atoms in axial positions. Intramolecular O-H center dot center dot center dot O hydrogen bonds are observed. In the crystal structure, molecules are linked into chains along the a axis by intermolecular O-H center dot center dot center dot O hydrogen bonds. The structure is further stabilized by pi-pi interactions between the pyridine rings of DENA units, with a centroid-centroid distance of 3.668 (2) angstrom.