Magnetorheological Elastomers (MREs) are viscoelastic composites of elastomeric matrices filled with magnetizable particles. Mechanical properties, such as stiffness and damping, can be continuously and rapidly controlled by an applied magnetic field. The oxidative stability of MR elastomers made from natural rubber (NR), ethylene-propene-diene-monomer (EPDM), and silicone RTV have been investigated using accelerated ageing techniques and mechanical testing. These advances include particle-modified systems such as silane coatings and polymer grafting techniques, which are combined with high-performance polymer matrices. Particle coating modifications were imaged and analyzed using both an Hitachi S-4300SE Field-Emission Scanning Electron Microscope equipped with an electron probe microanalyzer energy dispersive X-ray spectrometer (EDS) as well as a Jeol JSM-5900 scanning electron microscope also equipped with an EDS analyzer. Images of the particles/shells confirm the existence of the coating, and analysis was used to determine oxidative stability of the particle systems after a one month submersion in a simulated sea water environment. Enhanced oxidative stability of silicone and EPDM based magnetorheological elastomers is shown to dramatically improve with the use of surface modification reactions designed to produce thin protective layers surrounding the particles. A grafted polymer shell of poly(butyl acrylate) via atom transfer radical polymerization was investigated for its ability to provide resistance to oxidation.