  We report on partially overlapping XMM-Newton (~260 ks) and Suzaku (~100 ks)
observations of the iron K band in the nearby, bright Seyfert 1 galaxy Mrk 509.
The source shows a resolved neutral Fe K line, most probably produced in the
outer part of the accretion disc. Moreover, the source shows further emission
blue-ward of the 6.4 keV line due to ionized material. This emission is well
reproduced by a broad line produced in the accretion disc, while it cannot be
easily described by scattering or emission from photo-ionized gas at rest. The
summed spectrum of all XMM-Newton observations shows the presence of a narrow
absorption line at 7.3 keV produced by highly ionized outflowing material. A
spectral variability study of the XMM-Newton data shows an indication for an
excess of variability at 6.6-6.7 keV. These variations may be produced in the
red wing of the broad ionized line or by variation of a further absorption
structure. The Suzaku data indicate that the neutral Fe Kalpha line intensity
is consistent with being constant on long timescales (of a few years) and they
also confirm as most likely the interpretation of the excess blueshifted
emission in terms of a broad ionized Fe line. The average Suzaku spectrum
differs from the XMM-Newton one for the disappearance of the 7.3 keV absorption
line and around 6.7 keV, where the XMM-Newton data alone suggested variability.
