  In the context of f(R) modified gravity theories we determine that the black
holes existence is determined by the sign of a parameter dependent of the mass,
the charge, the spin and the scalar curvature. We obtain the different
astrophysical objects derived from the presence of different horizons.
Thermodynamics for this kind of black holes is studied for negative values of
the curvature, revealing that we can distinguish between two kinds of BH: fast
and slow.
