  We consider the most general non-Hermitian Hulthen potential to study the
scattering of spin-less relativistic particles. The conditions for CC, SS and
CPA are obtained analytically for this potential. We show that almost total
absorption occurs for entire range of incidence energy for certain parameter
ranges of the potential and hence term this as `black potential'. Time reversed
of the same potential shows perfect emission for the entire range of particle
energy. We also present the classical analog of this potential in terms of
waveguide cross section.
