  HD 52265 is the only known exoplanet-host star selected as a main target for
the seismology programme of the CoRoT satellite. As such, it will be observed
continuously during five months, which is of particular interest in the
framework of planetary systems studies. This star was misclassified as a giant
in the Bright Star Catalog, while it is more probably on the main-sequence or
at the beginning of the subgiant branch. We performed an extensive analysis of
this star, showing how asteroseismology may lead to a precise determination of
its external parameters and internal structure. We first reviewed the
observational constraints on the metallicity, the gravity and the effective
temperature derived from the spectroscopic observations of HD 52265. We also
derived its luminosity using the Hipparcos parallax. We computed the
evolutionary tracks for models of various metallicities which cross the
relevant observational error boxes in the gravity-effective temperature plane.
We selected eight different stellar models which satisfy the observational
constraints, computed their p-modes frequencies and analysed specific seismic
tests. The possible models for HD 52265, which satisfy the constraints derived
from the spectroscopic observations, are different in both their external and
internal parameters. They lie either on the main sequence or at the beginning
of the subgiant branch. The differences in the models lead to quite different
properties of their oscillation frequencies. We give evidences of an
interesting specific behaviour of these frequencies in case of helium-rich
cores: the ``small separations'' may become negative and give constraints on
the size of the core. We expect that the observations of this star by the CoRoT
satellite wi ll allow choosing between these possible models.
