For some years there have been experiments for developing a new aluminum oxide hydrate type filler in Hungary. The new materials are named Supralox. The products are relatively finely divided surface treated aluminum hydrates for replacing carbon black and white fillers or for use in combination with them to get optimum properties. The products have several important good parameters. The fillers can easily be dispersed in rubber and plastics, while the original physical parameters of the product remain intact and, what is more, some of them, like wear resistance, permanent set, electrical specific resistance, and fireproofing, are improved. Their incorporation in internal mixers or on a mill is quick, and 25-30% of energy can be saved compared with other fillers. The paper gives information about the authors' tests of using them for different rubber and plastic products.