This paper presents a procedure for manufacturing composites, a methodology for testing them and the cyclic properties of isotropic magnetorheological elastomers. The choice of a thermoplastic matrix and magnetically active iron powder as the filling (much larger than the carbonyl iron powder filling used so far) is expounded. A manufacturing technology has been developed. Possibilities for the experimental investigation of magnetomechanical properties have been created by building a measuring system enabling the testing of various elastomers in a wide range of mechanical and magnetic parameters. The effect of the magnetic field and that of the stress frequency on the damping properties of a selected elastomer (considered to be optimal) were examined.