Magnetorheological fluid compositions that include an aqueous carrier fluid, magnetic-responsive particles and an additive selected from bentonite or hectorite. This fluid exhibits excellent stability and is easy to re-disperse. Preferably, all the ingredients are inorganic. A magnetorheological material comprising an aqueous carrier fluid, magnetic-responsive particles having average diameters of 0.10 to 1000 μm and at least one additive selected from bentonite and hectorite.