We report the magnetic investigation of dinuclear Co(II) compounds on the base of hamiltonian which takes into account exchange interaction, zero-field splitting and Zeeman perturbation. The treatment of this hamiltonian is performed with the use of the irreducible tensor operator technique and symmetry of the system. A good agreement of the experimentally observed magnetic susceptibility and the results of calculation is obtained. (C) 2002 Published by Elsevier Science B.V.