Abstract: Treating the cosmological constant as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume, we reconsider the critical behaviour of charged AdS black holes. We complete the analogy of this system with the liquid-gas system and study its critical point, which occurs at the point of divergence of speci c heat at constant pressure. We calculate the critical exponents and show that they coincide with those of the Van der Waals system.