Abstract: The aim of this study was to predict the large time behaviour of solutions of diffusive prey-predator model, by using the notions of invariant region, energy estimates and exponential stability. The exponential stability was measured in terms of energy; defined by the square of L2-norm of solutions. By first constructing and proving the invariant region of the model, the occurrence of energy decaying exponentially in the long run was shown by using classical energy method. The interpretation and significance of such decay was discussed and some numerical evidences are presented so as to support the theoretical results.