We report on a medium deep XMM-Newton survey of the Marano Field and optical follow-up observations .
The mosaicked XMM-Newton pointings in this optical quasar survey field cover 0.6 deg ^ { 2 } with a total of 120 ksec good observation time .
We detected 328 X-ray sources in total .
The turnover flux of our sample is f _ { X } \sim 5 \times 10 ^ { -15 } erg cm ^ { -2 } s ^ { -1 } in the 0.2-10 keV band .
With VLT FORS1 and FORS2 spectroscopy we classified 96 new X-ray counterparts .

The central 0.28 deg ^ { 2 } , where detailed optical follow-up observations were performed , contain 170 X-ray sources ( detection likelihood ML > 10 ) , out of which 48 had already been detected by ROSAT .
In this region we recover 23 out of 29 optically selected quasars .
With a total of 110 classifications in our core sample we reach a completeness of \sim 65 % .
About one third of the XMM-Newton sources is classified as type II AGN with redshifts mostly below 1.0 .
Furthermore , we detect five high redshift type II AGN ( 2.2 \leq z \leq 2.8 ) .

We show that the true redshift distribution of type II AGN remains uncertain , since their lack of emission lines in a wide optical wavelength range hampers their identification in the redshift range 1 < z < 2 .
The optical and X-ray colors of the core sample indicate that most of the still unidentified X-ray sources are likely to be type II AGN .
We calculate absorbing column densities and show that the ratio of absorbed to unabsorbed objects is significantly higher for type II AGN than for type I AGN .
Nevertheless , we find a few unabsorbed type II AGN .
The X-ray hardness ratios of some high redshift type I AGN also give an indication of heavy absorption .
However , none of these type I objects is bright enough for spectral extraction and detailed model fitting .
Type I and II AGN cover the same range in intrinsic X-ray luminosity , ( 10 ^ { 43 } \leq L _ { X } \leq 10 ^ { 46 } ) , although type II AGN have a lower median intrinsic X-ray luminosity ( log L _ { X } \sim 44.0 ) compared to type I AGN ( log L _ { X } \sim 44.4 ) .

Furthermore , we classified three X-ray bright optically normal galaxies ( XBONGs ) as counterparts .
They show properties similar to type II AGN , probably harbouring an active nucleus .