  We study the spontaneous emission of charged bosons from supercritical
Coulomb potentials and charged black holes. We find the exact emission rate
from the Bogoliubov transformation by applying the tunneling boundary condition
on the Jost functions at the asymptotic boundaries. The emission rate for
charged bosons in the supercritical Coulomb potential increases as the charge
$Z\alpha > 1/2$ of the superatom and the energy of the bosons increase but is
suppressed for large angular momenta. We discuss physical implications of the
emission of charged bosons from superatoms and charged black holes.
