The mechanical properties, flame retardancy, hot-air ageing, and hot-oil ageing resistance of ethylene-vinyl acetate rubber (EVM)/hydrogenated nitrile-butadiene rubber (HNBR) /magnesium hydroxide (MH) composites were studied. With increasing HNBR fraction, elongation at break and tear strength of the EVM/HNBR/NM composites increased, whereas the limited oxygen index and Shore A hardness decreased slightly. Hot-air ageing resistance and hot-oil ageing resistance of the composites became better with increasing HNBR fraction. Thermal gravimetric analysis results demonstrated that the presence of MH and low HNBR fraction could improve the thermal stability of the composites. Differential scanning calorimeter revealed that the glass transition temperature (T-g) of the composites shifted toward low temperatures with increasing HNBR fraction, which was also confirmed by dynamic mechanical thermal analysis. Atomic force microscope images showed MH has a small particle size and good dispersion in the composites with high HNBR fraction. The flame retardancy, extremely good hot-oil ageing, and hot-air ageing resistance combined with good mechanical properties performance in a wide temperature range (-30 degrees C to 150 degrees C) make the EVM/HNBR/MH composites ideal for cables application. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3310-3318, 2009