The development of heterogeneous nanomaterials with high surface to volume ratio is crucial for enhancing the adsorption of water pollutants, such as toxic organic dyes. Here, we describe the synthesis of polyacrylonitrile (PAN) nanofibers coated with porous alumina nanolayers, and their application for adsorption of the organic dye methylene blue (MB). First, we produced PAN nanofibers by electrospinning, and then coated them with an aluminum alkoxide hybrid films fabricated using molecular layer deposition. Finally, we used thermal annealing to obtain the final PAN nanofibers coated with porous alumina nanolayers. We characterized the obtained nanostructured materials by scanning electron microscopy, transmission electron microscopy, N2 desorption/adsorption porosimetry (BET theory), and Fourier-transform infrared spectroscopy. The porous nanomaterials had a surface area of 631.79 m 2 /g that allowed reaching an adsorption efficiency of 88% with 10 ppm MB. The adsorption kinetics and isotherms were better described by a pseudo-first-order model and the Langmuir adsorption model, respectively, based on physical adsorption (monolayer adsorption) of the adsorbed molecules.