A thermodynamic analysis of hydrogen production from ethanol steam reforming (ESR) is carried out in the present paper. The influence of reactants molar ratio feed into the reforming stage (2.5 < mol Water /mol EtOH < 8), temperature (573 to 1173 K) and pressure (1 < P < 10 atm) over equilibrium compositions is studied. The direct method employed to analyze the system is the minimization of Gibbs free energy (MGFE) in conjunction with Lee-Kesler state equation, using the Kay mixing rules. The temperature and reactants molar ratio showed a positive influence on the hydrogen yield; ethanol conversion is 100% for the whole interval analyzed while the pressure affected greatly the hydrogen production. The carbon deposition exhibits a maximum value at temperatures around 773 K, and three reactions are proposed to describe the solid carbon formation in a wide temperature range based on thermodynamics and experimental predictions. The conditioning stages (mixing, vaporization, and heating) are studied in addition to the reaction to analyze the system quality by means of an exergetic method applying the 2nd law of thermodynamic.