Dimethyl bicyclobutane-l, 3-dicarboxylate was synthesized. Its homopolymer (PDBD) containing exclusively cyclobutane rings in its backbone was prepared by free radical polymerization. The copolymers of this bicyclobutane monomer with methyl methacrylate were also prepared. The glass transition temperature of the homopolymer is 159 degrees C, while those of its copolymers are 143 and 121 degrees C with 75/25 and 50/50 of the P(DBD/MMA) composition ratio, respectively. The T-g of PDBD homopolymer is substantially higher than that of commercial PMMA homopolymer despite a lower molecular weight, and is also much higher than that of its monomethyl cyclobutanecarboxylate analogue. These DBD homopolymer and copolymers also show better thermostability than the PMMA homopolymer. The weight-average molecular weight of homopolymer is 37,000. The polydispersities of these polymers are relatively narrow, with the range of 1.6-1.9. These polymers form clear colorless films resembling PMMA. film. The DBD homopolymer film shows a very similar optical cutoff compared to PMMA.