The scope of this paper is the definition of the most appropriate design parameters for a straw pellets torrefaction reactor of medium scale (capacity 1000 kg/h). However prior to the definition of these parameters, at subsequent level a thermodynamic tool is built and run, capable of predicting the heating value and the main characteristics (% solid residue, proximate analysis) of the torrefied straw pellets, always with parameters: the residence time and temperature.