Composites of rubbers such as ethylene – propylene and acrylonitrile – butadiene with micro size Fe¬3O4, Fe2O3, and nano size Fe3O4 as the fillers were tested. Iron oxides were found to be active fillers which improved mechanical properties of elastomers. Additionally, they also changed their magnetic properties. Furthermore, the surface of micro size Fe3O4 was modified to upgrade mechanical properties of the vulcanizates. Itaconic acid, methacryloxypropyltrimethoxysilane and monododecyl maleate were used as modifying agents. To improve dispersion of applied fillers in polymers matrix, non-ionic (NF-PEG), anionic (calcium stearate ), cationic (DTAB, DTAC, DDAB, CTAD) and ionic liquids (HMIMBF4, BMIMPF6, OMIMPF6) were used. It was observed that both non-modified and modified micro iron oxides and nano iron oxides improved the properties of the vulcanizates the most effectively.