  We present the results of a 127 ks XMM-Newton observation of the broad-line
radio galaxy 3C 120 performed simultaneously with RXTE. The time-averaged
spectrum is Seyfert-like, with a reflection amplitude R ~ 0.5, and a neutral Fe
K line with equivalent width ~53 eV. The line is slightly broadened with a
FWHM$\approx 10^4$ km s$^{-1}$. This is consistent with arising from an
accretion disc radius of $\ga 75$ $GM/c^2$ at an inclination angle of ~10
degrees, consistent with the limit of < 14 degree derived from the radio jets.
At low energies the spectrum requires excess absorption above the Galactic
value and a soft excess which is best fit with a bremsstrahlung model
(kT=0.3-0.4 keV). The total luminosity in the bremsstrahlung component is just
under half of the total hard X-ray luminosity. Weak O VII and O VIII edges are
detected with high precision, suggesting the presence of a warm absorber
component. A two-component ionized disc model, with a very highly ionized
reflector presumably arising from very close to the black hole, is only a small
improvement over a truncated disc model. The strength of the soft X-ray
emission features produced by the distant neutral reflector are overpredicted
in our solar abundance model, implying that the heavy metal abundance in 3C 120
is subsolar. The total count-rate declined by 20 per cent over the course of
the long observation, while small-scale rapid variability was present at the
level of a few percent. A possible increase in the Fe K line flux, significant
at the 90 per cent level, was identified at ~80 ks in the observation. The
total unabsorbed luminosity of 3C 120 implies that it is accreting close to its
Eddington rate, consistent with a model of an ionized thick disc. A connection
between accretion disc thickness and radio jet production is discussed.
