Tuning of hole transport and optical properties were accomplished in polyaniline incorporated flexible paper during vapor phase polymerization process. Vapor phase polymerization of aniline using FeCl3 as polymerizing agent was done in a reaction chamber, where the concentration of FeCl3 on paper played the key role in tuning its properties. The energy band gap and electrical conductivity of the polyaniline incorporated paper have been tuned effectively during the polymerization process. The band gap changes from 2.45 eV to 2.65 eV, when the electrical sheet resistance varied from 1.0 x10(5) omega/& to 4.33 x10(7) omega/& in response to the different FeCl3 concentration. The electrical sheet resistance can be tuned within a range of two order of its value. Polymer-based electronic materials with outstanding electrical conductivity due to their delocalized molecular orbitals are of great interest in the recent development of materials chemistry and physics. Paper being a flexible substrate and incorporated with a hole transporting medium like polyaniline in its emeraldine base form will find its significant role in designing flexible electronic devices. POLYM. ENG. SCI., 58:2249-2255, 2018. (c) 2018 Society of Plastics Engineers