A method for the study of the flow field around a re-entry vehicle is discussed. Flow field at re-entry is characterized by high energy with the presence of dissociative effects. To take into account such dissociative effects, a simplified model based on the use of a modified specific heat has been adopted and discussed. A numerical method has been validated by means of a comparison with available data of Riley and De Jarnette [ 1]. Numerical results are also presented for a YES-2 re-entry capsule in the correspondence of three of the most critical flight conditions.