Abstract: The process of metal plating an object formed out of a cyclic olefin polymer is improved by first immersing the object in an organic solvent, such as an aromatic hydrocarbon or a halogenated aliphatic hydrocarbon, that serves to swell the object at its surface, for example sufficiently to increase its weight by about 0.1 to 70%. In this way objects molded out of, for example, poly(dicyclopentadiene) can be pre-etched by being immersed in xylene for 5 minutes at room temperature, and then plated by the electroless deposition of nickel on the surface of the etched part. The pre-etching facilitates adhesion of the plating metal to the surface.