  Based on high-resolution observations (R=60000 and 75000), we have studied
the optical spectral variability of the star BD+48 1220 (IRAS05040+4820). We
have measured the equivalent widths of numerous absorption lines of neutral
atoms and ions at wavelengths from 4500 to 6760 AA, as well as the
corresponding radial velocities. We use model atmospheres to determine
Teff=7900K, log g=0.0, microturbulence velocity xi_t=6.0, and the abundances
for 16 elements. The star's metallicity differs little from the solar value:
[Fe/H]=-0.10 dex. The main peculiarity of the chemical composition of the star
is a large He-excess, derived from the HeI 5876 A absorption, [He/H]=+1.04, and
the equally large O-excess, [O/Fe]=+0.72 dex. The C-excess is small,
[C/Fe]=+0.09 dex, and the ratio [C/O]$\le$ 1. We obtained a revised relation
for the light-metal abundances: [Na/Fe]=+0.87 with [Mg/Fe]=-0.31. The barium
abundance is low, [Ba/Fe]=-0.84. The radial velocity of the star measured from
photospheric absorption lines over three years of observations varies in the
interval V_sun = -(7 - 15) km/s. Time variable differential line shifts have
been revealed. The entire set of available data (the luminosity Mv~-5m,
velocity V_lsr~-20 km/s, metallicity [Fe/H]=-0.10, and peculiarities of the
optical spectrum and chemical composition) confirms the status of BD+48 1220 as
a post-AGB star with He- and O-excesses belonging to the Galactic disk.
