We present a detailed analysis of the mass distribution in the rich and distant cluster of galaxies Cl0024+17 .
X-ray data come from both a deep ROSAT HRI image of the field [ Böhringer et al. , 1999 ] and ASCA spectral data .
Using a wide field CCD image of the cluster , we optically identify all the faint X-ray sources , whose counts are compatible with deep X-ray number counts .
In addition we marginally detect the X-ray counter-part of the gravitational shear perturbation detected by Bonnet et al . [ Bonnet et al. , 1994 ] at a 2.5 \sigma level .
A careful spectral analysis of ASCA data is also presented .
In particular , we extract a low resolution spectrum of the cluster free from the contamination by a nearby point source located 1.2 arcmin from the center .
The X-ray temperature deduced from this analysis is T _ { X } = 5.7 ^ { +4.9 } _ { -2.1 } keV at the 90 % confidence level .
The comparison between the mass derived from a standard X-ray analysis and from other methods such as the Virial Theorem or the gravitational lensing effect lead to a mass discrepancy of a factor 1.5 to 3 .
We discuss all the possible sources of uncertainties in each method of mass determination and give some indications on the way to reduce them .
A complementary study of optical data is in progress and may solve the X-ray/optical discrepancy through a better understanding of the dynamics of the cluster .