This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record. ; Density functional theory (DFT) study of polypyrrole-TiO2 composites has been carried out to explore their optical, electronic and charge transfer properties for the development of an efficient photocatalyst. Titanium dioxide (Ti16O32) was interacted with a range of pyrrole (Py) oligomers to predict the optimum composition of nPy-TiO2 composite with suitable band structure for efficient photocatalytic properties. The study has revealed that Py-Ti16O32 composites have narrow band gap and better visible light absorption capability compared to individual constituents. The simulated results of band structure (band gap, and band edge positions), molecular orbitals, and UV–vis spectra of the optimized nPy-Ti16O32 systems strongly supportthe existence of strong interactions between Py and TiO2 in the composite. A red-shifting in max, narrowing band gap, and strong intermolecular interaction energy (-41 to −72 kcal/mol) of nPyTi16O32 composites confirm the existence of strong covalenttype interactions. Electron−hole transferring phenomena are simulated with natural bonding orbital analysis where Py oligomers found as donor and Ti16O32 as an acceptor in nPy-Ti16O32 composites. ; H.U acknowledges the partial financial support of the UK Solar Fuel Network (SFN).