  Aims: We aim at estimating the spectral energy distributions (SEDs) and the
physical parameters related to the black holes harbored in eight high
X-ray-to-optical (F_X/F_R>10) obscured quasars at z>0.9 selected in the 2--10
keV band from the HELLAS2XMM survey.
  Methods: We use IRAC and MIPS 24 micron observations, along with optical and
Ks-band photometry, to obtain the SEDs of the sources. The observed SEDs are
modeled using a combination of an elliptical template and torus emission (using
the phenomenological templates of Silva et al. 2004) for six sources associated
with passive galaxies; for two point-like sources, the empirical SEDs of red
quasars are adopted. The bolometric luminosities and the M_BH-L_K relation are
used to provide an estimate of the masses and Eddington ratios of the black
holes residing in these AGN.
  Results: All of our sources are detected in the IRAC and MIPS (at 24 micron)
bands. The SED modeling described above is in good agreement with the observed
near- and mid-infrared data. The derived bolometric luminosities are in the
range ~10^45-10^47 erg s^-1, and the median 2--10 keV bolometric correction is
~25, consistent with the widely adopted value derived by Elvis et al. (1994).
For the objects with elliptical-like profiles in the K_s band, we derive high
stellar masses (0.8-6.2)X10^11 Mo, black hole masses in the range
(0.2-2.5)X10^9 Mo, and Eddington ratios L/L_Edd<0.1, suggesting a low-accretion
phase.
