  This paper presents preliminary results of a systematic study on the X-ray
spectral variability of PG quasars with XMM-Newton. We concentrate on those
objects, whose X-ray spectra are well fit in the framework of the ``double
Comptonization'' model. On short (<1000 seconds) timescales, variability
between the soft (E<2 keV) and the hard (E>2 keV) bands is uncorrelated. In the
two objects, for which observations at different epochs are available, spectral
variability in the soft X-ray regime is unveiled. Its timescale is constrained
in the range between ~1 week and ~1 year.
