  The technique of estimating redshifts using photometric rather than
spectroscopic observations has recently received great attention due to its
simplicity and the accuracy of the results obtained. In this work, we estimate
photometric redshifts for an X-ray selected QSO sample. This is the first time
this technique is applied on such a sample. We first calculate the accuracy of
the results obtained by comparing photometric to spectroscopic redshifts for a
sub-sample of our QSO sample: for the majority (~67%) of the objects in this
sub-sample, photometric redshift estimates are correct within Dz<0.3. We then
derive the photometric redshift distribution for the whole QSO sample. In the
future, we expect to use the photometric redshift distribution in order to
derive the distributions of properties such as the Hardness Ratio and hence the
hydrogen column density, the luminosity function etc. As an example, we
estimate here the dependence of the Hardness Ratio of the QSO sample on
photometric redshift.
