Inorganic nanoparticles of a variety of materials have been obtained by chemical methods. Under the kinetic control, small variations in the synthesis recipe may yield crystals of different sizes, shapes and structures. Co nanocrystals are of particular interest: besides achieving size control, at least three nearly isoenergetic crystal structures (face-centered cubic, hexagonal close-packed and epsilon) can be synthesized, and shape control (spheres, prisms, cubes, rods and disks) is also possible. Although shape and structure should be intrinsically related, the relationship between these two characteristics has not been deeply explored up to this moment. Here, we present our latest results on Co nanoparticles, analyzing the influence of some parameters on particle shape and structure. In particular, the influence of ligand type and temperature has been tackled.