New polymeric products containing cyclopropane groups in the macromolecules have been obtained by catalytic cyclopropanation of syndiotactic 1,2-PB with diazomethane. A comparative estimate of the activity and regioselectivity of the catalysts used in the 1,2-PB cyclopropanation is given. It has been shown that varying the catalyst nature allows one to control the cyclopropanation process and to obtain modified polymers with predefined structure and degree of functionalization. The effect of the degree of modification on the molecular characteristics and properties of cyclopropanated polymers, such as viscosity of solutions and melts, glass transition point, crystallinity and thermal stability, has been studied. It has been shown that the incorporation of cyclopropane groups into macromolecules of syndiotactic 1,2-PB gives amorphous thermoplastic polymeric products that are rather energy rich and are of practical interest.