A magnetorheological fluid composition comprising magnetizable particles in a liquid metal carrier fluid, wherein the liquid metal carrier fluid comprises a metal, a metal alloy, or a solder composition having a melting point from about -40.degree. C. to about 300.degree. C., a boiling point greater than 300.degree. C., and a viscosity greater than about 0.1 centipoise (cp) at the melting point of the liquid based metal carrier fluid. The magnetizable particles can comprise low aspect ratio magnetizable particles, high aspect magnetizable particles, or a combination thereof. Also disclosed herein are high temperature magnetorheological devices operating at temperatures greater than 100.degree. C., and comprising the magnetorheological fluid composition.