The oriented 1D nanostructure arrays of PANI have great potential applications in various devices. In this paper, we report a simple and facile one-step template-free way to assemble highly oriented arrays of PANI nanofibers using chemical oxidative polymerization on the glass and polymer flexible substrates. The diameters of the individual nanofibers range from 10 nm to 33 nm, and the average length of the aligned nanofibers is up to 48-139 nm. The PANI nanofiber arrays can be uniformly distributed on the whole substrates via this method, which are confirmed by the results of SEM images and Raman mapping. The as-prepared PANI nanofiber arrays can be potentially used in flexible low-voltage electronics, anti coatings, self-cleaning surfaces and chemical sensors, and so on. (C) 2017 Elsevier B.V. All rights reserved.