  We report the discovery of hard X-ray delays in the X-ray emission of the
Seyfert 1 galaxy Mrk 110, based on a long XMM-Newton observation. Cross
correlation between the X-ray light curves of different energy bands reveals an
energy dependent delay ranging from a few minutes to an hour. We find that the
energy spectrum can be modeled by Comptonization of disk blackbody photons. The
energy dependent delay can be modeled as due to the effect of Comptonization in
a hot plasma confined within 10 Schwarzschild radius of the black hole. We
discuss our results in the context of inverse Comptonization of the soft
photons by highly energetic plasma.
