Ethanol reforming in microwave argon plasma, operating at 2.45 GHz under atmospheric pressure and vortex gas flow has been investigated. Hydrogen, carbon monoxide and solid carbon are the main outlet products. H-2 and CO have been detected by mass spectrometry (MS) and Fourier transform infrared spectroscopy (FT-IR) whereas "black" carbon deposited at the wall has also been observed. The hydrogen yield has an average value of 98.4%, for ethanol fluxes in the range 4-15 sccm. An increase of about 32% in the energetic hydrogen mass yield has been observed as compared to laminar flow conditions. A theoretical model based on a set of non-linearly coupled differential equations accounting for the gas thermal balance and the chemical kinetics has been developed. An integral reaction scheme considering ethanol decomposition via two parallel channels was proposed and experimentally validated. Taking into account the diffusion of carbon into colder zones, the formation of solid carbon has also been analyzed. Some part of the solid carbon is deposited on the tube wall while another part is carried away with the outlet gas flow. The theoretical predictions for the H-2 and CO relative densities agree well with experimental data. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.