Butyl rubber (IIR) has outstanding resistance to attack by oxygen and ozone, and good chemical resistance to a large number of organic and inorganic media. Due to the absence of double bonds in the backbone, IIR products can withstand prolonged exposure to heat, and are usually stable in dilute acids and alkalis. IIR has exceptional low gas and moisture permeability which makes it ideal for inner tubes and high pressure/vacuum applications under demanding conditions.

IIR elastomers are sometimes halogenated with chlorine or bromine to improve their resistance to certain chemical media, but at the expense of electrical insulation and moisture resistance. The introduction of halogen also increases the reactivity of the unvulcanized rubber and improves adhesion to other unsaturated rubbers.