Two magnetodensimetric cells with high gradient magnetic separation (HGMS) axial structure are presented. The method of magnetodensimetric separation is based on the buoyant force exercised by a magnetic fluid, particularly a ferrofluid, on a solid particle when it is placed in a nonuniform magnetic field. The equations of motion of the particles entering cells through a well-delimited surface are solved. By studying the trajectories of the particles we prove the possibility of efficient separation of particles with different densities.