The title compound, (C8H12NO)2[Co(H2P2O7)2(H2O)2]·2H2O, crystallizes isotypically with its Mn(II) analogue. It consists of alternating layers of organic cations and inorganic complex anions, extending parallel to (100). The complex cobaltate(II) anion exhibits -1 symmetry. Its Co(2+) atom has an octa-hedral coordination sphere, defined by two water mol-ecules in apical positions and two H2P2O7 (2-) ligands in equatorial positions. The cohesion between inorganic and organic layers is accomplished by a set of O-H⋯O and N-H⋯O hydrogen bonds involving the organic cation, the inorganic anion and the remaining lattice water mol-ecules.