  In this paper we have studied the extended phase space thermodynamics in the
canonical ensemble of black holes in massive gravity in AdS space. The black
holes considered here belong to a theory of massive gravity where the graviton
gain a mass due to Lorentz symmetry breaking. We have computed various
thermodynamical quantities such as temperature, pressure, Gibbs free energy and
specific heat capacity. The local and the global thermodynamical stability of
the black holes are studied in detail. For a specific value of the parameter in
the theory, the black holes undergo a first order phase transition similar to
the Van der Waals phase transitions between gas and liquid under constant
temperature. This transition is between the small and the large black hole. The
critical exponents are computed at the critical values and shown to be the same
as for the Van der Waals critical exponents.
