This work was done to explore the effect of poly(pyrrole) on the facilitated transport of 1-hexene, 1,5-hexadiene, cyclohexene, styrene and ethylbenzene through water-swollen Nafion(R) 112. The experiments were carried out in the perstraction mode with single-component feed solutions consisting of I M unsaturated hydrocarbon in isooctane. The decrease in the facilitation factors revealed that the facilitated transport mechanism become less effective when poly(pyrrole) was incorporated into the membrane. This was attributed to the steric effect of poly(pyrrole) which prevented the hydrocarbons from accessing to some Ag+ ions. Double bonds in poly(pyrrole) chain might also compete with the hydrocarbons for the complexation with Ag+ ions. In addition, the presence of poly(pyrrole) decreased the water content of the membranes from 12.2 g H2O/g wet membrane to 10.9 g H2O/g wet membrane. Mobility of Ag+ ions in the membrane could then be lowered, limiting the ability of the carriers to complex with the penetrants. Atomic absorption measurements showed that the number of Ag+ ions in the membrane remained unchanged after poly(pyrrole) was incorporated into Nafion(R).