This study illustrates the design of statistical analysis by Taguchi methodology to obtain nanostructured fly ash by planetary ball milling. An orthogonal array and analysis of variance were employed to analyze the effect of milling parameters. A class-F fly ash was subjected to planetary ball milling induced mechano-chemical activation aided by a surfactant. Ball milling parameters, such as ball-to-powder weight ratio, type and quantity of surfactant and type of medium were varied as guided by the Taguchi design. The nanostructured fly ash was characterized by dynamic light scattering, BET surface area analysis, X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy. The ball-to-powder weight ratio and the surfactant type are the major influencing factors on lower crystallite size and average particle size and higher specific surface area. The surface modification of fly ash was confirmed by FTIR spectroscopy. The nano fly ash produced by this method has a wide application potential in polymer industries as reinforcement in composites. (C) 2015 Elsevier B.V. All rights reserved.