We prepared the antiferromagnetic Ca2CoWO6, Sr2CoWO6 and Ba2CoWO6 double perovskites with different crystalline structures, which are monoclinic, tetragonal and cubic respectively. The crystalline structures affect the Co-O distances and the local octahedral symmetry. Magnetic susceptibility experiments were performed as a function of magnetic field and temperature. We found that the effective magnetic moment (mu(eff)) of Co2+ is partially unquenched and we also found that mu(eff) increases with the average of Co-O distances that form the CoO6 octahedra. A simple model associates the behavior of the effective magnetic moment with crystal field effects. (C) 2012 Elsevier Ltd. All rights reserved.