This study is focused to optimising a bio-ethanols auto-thermal reforming (ATR) process over 5% Rh/Al2O3 catalyst homemade, to produce syn-gas for fuel cell application. The effect of oxygen addition for a given S/C molar ratio ranging from 2.1 to 6.3 at T = 923 K was investigated, varying the O-2/EtOH molar ratio between 0.2 and 1.1. The results have identified an optimum range where the ethanol conversion is 100%, CH4 and CO productions go down and hydrogen yield reaches a maximum before decreasing because of the prevalent oxidizing action of oxygen. The obtained data, compared with those from steam reforming (SR) process, gave a very clear indication about the potentiality of ATR process. (C) 2003 Elsevier Science B.V. All rights reserved.