  We report results on a 40 ks XMM-Newton observation of the Type 2 quasar 3C
234. Optical spectropolarimetric data have demonstrated the presence of a
hidden broad-line region in this powerful (M_V <~ -24.2 after reddening and
starlight correction) narrow-line FRII radio galaxy. Our analysis is aimed at
investigating the X-ray spectral properties of this peculiar source which have
remained poorly known so far. We analyze the 0.5--10 keV spectroscopic data
collected by the EPIC cameras in 2006. The X-ray spectrum of this radio-loud
quasar is typical of a local Compton-thin Seyfert 2 galaxy. It exhibits strong
absorption (Nh~3.5 x 10^{23} cm^{-2}) and a narrow, neutral Fe Kalpha emission
line with an equivalent width of ~140+/-40 eV. Our observation also reveals
that the soft portion of the spectrum is characterized by strong emission lines
with a very low level of scattered primary continuum. A possible explanation of
these features in terms of thermal emission from a two-temperature
collisionally ionized plasma emission seems to be unlikely due to the high
luminosity estimated for this component (L(0.5-2) ~ 6 x 10^{42} erg/s). It is
likely that most of the soft X-ray emission originates from a photoionized
plasma as commonly observed in obscured, radio-quiet Seyfert-like AGNs. This
X-ray observation has definitively confirmed the presence of a hidden quasar in
3C 234. The line-rich spectrum and the steepness of the hard X-ray continuum
(Gamma ~ 1.7) found in this source weaken the hypothesis that the bulk ofthe
X-ray emission in radio-loud AGNs with high excitation optical lines arises
from jet non-thermal emission.
