Abstract: The present invention provides a method for hydrogenating a metathesis polymer solution obtained by polymerization in the presence of a metathesis polymerization catalyst comprising (a) the catalyst component of a transition metal compound and (b) the co-catalyst component of a metal compound by bringing the above solution into contact with hydrogen, without adding an inactivating agent for the metathesis polymerization catalyst, that is, with the solution left to contain the catalyst, in the presence of a hydrogenation catalyst comprising a transition metal compound (c) and a reductive metal compound (d) and if necessary by adding an acid-binding compound.

Abstract: The present invention provides the hydrogenated product of a thermoplastic norbornene polymer excellent in characteristics as optical materials by reducing the residual amounts of the transition metal atoms originating from the polymerization catalyst used at the polymerization to 1 ppm or less of the hydrogenated product.Reduction of the residual amounts to below the desired level is attained by treating the reaction solution with the adsorbent during or after production of the hydrogenated product from the thermoplastic norbornene polymer.The hydrogenated product of the thermoplastic norbornene polymer thus obtained in which the residual amounts of the transition metal atoms are 1 ppm or less, has a wide utilization field, including a material for optical articles having excellent utilization characteristics such as substrates for optical elements, lenses and the like.