Toothed belt comprising a body, a plurality of resistant inserts or cords and a plurality of teeth extending from at least one surface of the body; the teeth are coated with a coating fabric. The body is made of a first elastomeric material formed. The fabric is treated with a fabric treatment comprising a second elastomeric material. The resistant inserts or cords are treated with cord treatment comprising a third elastomeric material. The first, second and third elastomeric material are formed of a mixture of one or more copolymers obtained from diene monomers and monomers containing nitrile groups, in which the nitrile groups are between 30 wt % and 39 wt %.