We present joint X-ray and optical observations of the high redshift ( z \simeq 0.83 ) lensing cluster CLJ 0152.7 - 1357 made with the Chandra X-ray Observatory and the Keck 
telescope .
We confirm the existence of significant substructure at both X-ray and optical wavelengths in the form of two distinct clumps , whose temperatures are 6.6 _ { -1.5 } ^ { +2.4 } keV and 5.7 _ { -1.6 } ^ { +2.9 } keV , respectively .
The X-ray surface brightness profiles of the two clumps can be fitted by either a single \beta -model or an NFW-like profile ; the latter giving better fits to the central regions .
We find that the X-ray derived mass of this cluster is in good agreement with independent lensing measurements .
While its appearance indicates that the cluster has not reached a dynamical equilibrium state , its X-ray luminosity L _ { X } , temperature T and dynamical mass M are consistent with the well-defined L _ { X } - T and M - T relations for low-redshift galaxy clusters , which suggests that the dynamical properties of the clusters have remained almost unchanged since z \approx 0.8 .