A type of electrorheological (ER) system, denoted the magnetic materials-based electrorheological fluids, is introduced. The solid particles of this system are 40–50 &mgr;-microspheres obtained by the sol–gel processing of a ferroelectric material containing a ferromagnetic component. Since the solid material is magnetic, the presence of a small magnetic field, such as that from a small permanent magnet, can suspend the microspheres in liquid. The incorporation of a small amount of magnetic materials thereby solves the long standing problem of particle sedimentation in ER fluids. It is found that this type of ER fluid is very stable and exhibits a strong ER effect at low electric field. ©1997 American Institute of Physics.