Butyl rubber (IIR) produced by cationic polymerization is copolymer of isobutylene with a small amount of isoprene. Halogenated butyl rubbers (Halogenated IIR) reacted with chlorine or bromine with IIR in organic solvent has been produced in industry. One of the characteristic properties of IIR and Halobutyl is impermeability to air. The major uses of these rubbers are innertubes for tire. In this paper, manufacturing methods and properties of IIR are reported.