Polyamide 6/titanium dioxide (PA6/TiO2) composite nanofibers were prepared as templates via electrospinning-electrospraying process, in which TiO2 nanoparticles were inserted into PA6 nanofibers mat, and then PA6/TiO2/polyaniline (PANI) composite nanofibers were fabricated by in-situ polymerization of aniline. Structural and morphological of the prepared composite nanofibers were carried out through scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Their abilities to detect ammonia were evaluated by a home-made test system. It was found that p-n junction was formed at the interface between PANI and TiO2. And due to the p-n junction, the PA6/TiO2/PANI composite nanofibers exhibited good reproducibility, selectivity and apparent improvement in response than that of PA6/PANI composite nanofibers. (C) 2014 Elsevier B.V. All rights reserved.