Aryloxo-modified half-titanocenes, CpTiCl2(O-2,6-iPr2C6H3) [Cp=Cp* (1), tBuC5H4 (2)], catalyze terpolymerization of ethylene and styrene with -olefin (1-hexene and 1-decene) efficiently in the presence of cocatalyst, affording high-molecular-weight polymers with unimodal distributions (compositions). Efficient comonomer incorporations have been achieved by these catalysts. The content of each comonomer (-olefin, styrene, etc.) could be controlled by varying the comonomer concentration charged, and resonances ascribed to styrene and -olefin repeated insertion were negligible. The terpolymerization with p-methylstyrene (p-MS) in place of styrene also proceeded in the presence of [PhN(H)Me2][B(C6F5)4] and AliBu3 cocatalyst, and p-MS was incorporated in an efficient matter, affording high-molecular-weight polymers with uniform molecular weight distributions. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 25652574