The structure of the mixed diphosphate ZnCoP2O7 is characterized by the cationic order between the diamagnetic and paramagnetic ions. The Co2+ ions are lodged in octahedral sites whereas the Zn2+ ions occupy distorted square pyramids. The octahedrons CoO6 share a common edge and form dimers Co2O10 separated by dimers of zinc, which confers to this compound a low dimensionality character. Magnetic susceptibility shows that ZnCoP2O7 is antiferromagnetic. The correlation magneto-structural confirms the presence of Co2+ dimers. The magnetic specific heat of ZnCoP2O7 shows a large maximum characteristic of a low dimensionality system.