  Doppler images in Balmer, HeI, HeII and CII lines, and simultaneous I-band
photometry of the polar MR Ser are presented and analyzed. The Balmer and
Helium Doppler tomograms of this bright polar at high mass transfer state show
the emission from the accretion flow and the heated surface of the companion
star. As a result of a comparison between the Doppler tomograms the ionization
structure of the flow could be constrained. The highest ionization region was
found in the vicinity of the magnetospheric radius. Photoionization modeling of
the accretion column indicates that the Balmer and Helium emission line
production in this system can be explained by the central soft Xray
illumination only. The orbital ephemeris of MR Ser has been revised.
