  We present an analytical study of chaos in a charged black hole in the
extended phase space in the context of the Poincare-Melnikov theory. Along with
some background on dynamical systems, we compute the relevant Melnikov function
and find its zeros. Then we analyse these zeros either to identify the temporal
chaos in the spinodal region, or to observe spatial chaos in the small - large
black hole equilibrium configuration. As a byproduct, we derive a constraint on
the Black hole charge required to produce chaotic behaviour. To the best of our
knowledge, this is the first endeavour to understand the correlation between
chaos and phase picture in black holes.
