Theoretical penetrant concentration profiles under steady-state pervaporation conditions were generated using a newly developed transport model. The transport model assumes the presence of an imaginary phase (liquid or vapor) which is in thermodynamic equilibrium with the membrane phase. Theoretical profiles were compared with experimental concentration profiles. The calculation for the phase boundary between imaginary liquid and vapor phases was also performed using the transport model. The present work is the first theoretical work that can reconstruct penetrant profiles inside the membrane showing concentration polarization.