Novel cyclic olefin polymers (COPs) with excellent transparency and high glass-transition temperature (T-g) synthesized from bulky norbornene derivative, exo-1,4,4a,9,9a,10-hexahydro-9,10(1',2')-benzeno-l,4-methanoanthracene (HBMN), and cis-cyclooctene (COE) by ring-opening metathesis copolymerization utilizing the first-generation Grubbs catalyst, RuCl2(PCy3)(2)(CHPh), and subsequent hydrogenation was reported herein. To get amorphous copolymers, it was of great importance to control the feed ratios and the polymerization time for gradient copolymerization. All these copolymers showed very high T(g)s (141.1-201.2 degrees C), which varied with the content of HBMN. The films of the gradient copolymers with only one T-g were highly transparent. On the contrary, all the block copolymers synthesized through sequential addition showed two thermal transition temperatures, T-g and melt temperature (T-m), and the films of these block copolymers were opaque. The mechanical performances of the COPs were also investigated. It is the first report that transparent COP could be prepared from bulky norbornene derivative and monocyclic olefin. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3240-3249