A series of novel hybrid poly(acetoxylstyrene-co-isobutylstyryl-POSS)s (PAS-POSS) and poly(vinylpyrrolidone-co-isobutylstyryl-POSS)s (PVP-POSS) are synthesized and characterized. The POSS content in these hybrids can be controlled by varying the monomer feed ratio. The polyhedral oligosilsesquoixane (POSS) moiety can effectively increase the T-g of the resultant organic/inorganic hybrid polymer at a relatively high POSS content and produce the hybrid copolymer with narrower molecular weight distribution. The FTIR spectra are used to investigate the structure-property relationship of these hybrid polymers, and the T-g enhancement mechanism is discussed in detail.