Two poly(trimethylsilyldiphenylacetylene) membranes containing different contents of fluorine-containing groups were prepared by direct perfluorodecylation of poly(trimethylsilyldiphenylacetylene) (poly 1) in the membrane state using different ratios of (perfluorodecyl)phenyliodonium triflates to the phenyl groups in the polymer. The resulting perfluorodecylated poly(trimethylsilyldiphenylacetylene) (poly 2a and poly 2b) membranes were self-standing and tough. The two membranes showed better performance in oxygen permselectivity compared with all the membranes reported by many researchers. The performance (PO2 &gt
103 barrer and α = PO 2/PN2 = 2.9) of the poly 2a membrane having a lower content of the fluorine groups located on the upper boundary line reported by Robeson in 2008. The poly 2b membrane having a higher content of the fluorine groups was one of the polymers having the highest PO2 values (PO 2 &gt
104 barrer) in all the polymers reported.