Terpolymerization of norbornene (NB), isoprene (IP), and 1-octene was achieved by using fluorenylamido-ligated titanium catalyst, which showed very high activity for the copolymerization of NB and various -olefins. The content of IP in the terpolymer was controlled by the feed ratio and reaction temperature up to 7 mol %. The incorporated IP was mainly inserted in 1,4-addition. The polymer was dissolved into common solvents such as toluene and chloroform, which enabled the preparation of a transparent film by solution casting process. The degradation temperature of the terpolymer was comparable with other cyclic olefin copolymers and the glass transition temperature (T-g) was higher than that of NB-1-octene copolymer with almost the same NB content. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2136-2140