The asymmetric unit of the title complex, [Ni(C6H6N2O)(2)(H2O)(4)](C8H5O3)(2)center dot 2H(2)O, contains one-half of the complex cation with the Ni-II atom located on an inversion center, a 4-formylbenzoate (FB) counter-anion and an uncoordinated water molecule. The four O atoms in the equatorial plane around the Ni atom form a slightly distorted square-planar arrangement and the slightly distorted octahedral coordination is completed by the two N atoms of the isonicotinamide (INA) ligands at a sligthly longer distance in the axial positions. The dihedral angle between the carboxylate group and the attached benzene ring is 8.14 (11)degrees, while the pyridine and benzene rings are oriented at a dihedral angle of 3.46 (6)degrees. In the crystal structure, O-H center dot center dot center dot O, N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds link the molecules into a three-dimensional network. pi-pi Contacts between the benzene and pyridine rings [centroid-centroid distance = 3.751 (1) angstrom] may further stabilize the crystal structure.