The objective of our study was to develop a new class of polyaniline/titanium dioxide (PANI-TiO2) nanocomposites with characteristic one dimensional morphology. PANI-TiO2 nanocomposites were characterized by SEM-EDX, TEM, UV-DRS, TGA and XRD techniques. The PANI-TiO2 nanocomposite was investigated for the photocatalysis and antibacterial properties; the latter was hitherto unscreened. The photocatalytic and antibacterial activity was tested using methylene blue (MB) as model dye and Escherichia coli (E. coli) as a model organism respectively. Antibacterial efficiency was analyzed by optical density and morphological damage was observed by TEM. In contrast to pristine polyaniline (PANI), lower concentrations of PANI-TiO2 nanocomposite were needed to strongly inhibit the growth of wild-type E. coli. The nanocomposite has exceptionally good antibacterial activity against E. coil. Admirable photo-degradation efficiency against MB dye was achieved under visible light which could be attributed by the promotion of charge separation efficiency caused by the synergy between PANI and TiO2. Undoubtedly our results indicate that PANI-Ti02 nanocomposite could be useful for multiple applications such as a very good candidate for water purification, antibiofouling, and disinfection of chemical and biological pollutants. (C) 2014 Elsevier B.V. All rights reserved.