A rotor for a motor or for a radial flux electromagnetic generator having a cylindrical support housing a plurality of magnets (4), characterised in that the cylindrical support comprises a cylindrical mesh (5a) having mesh elements each defining a recess (5) for a respective individual magnet (4), each recess (5) having internal dimensions that are just sufficient to allow the introduction of a individual magnet (4) in its interior while leaving a space between the recess (5) and the individual magnet (4) filled by a fibre-reinforced resin, the mesh (5a) being made from a fibre-reinforced insulating material, the rotor comprising a non-conductive composite layer coating the individual magnets (4) and the mesh (5a).