  We present our discovery observations and analysis of RDCS1317+2911, z =
0.805, and RDCS1350+6007, z= 0.804, two clusters of galaxies identified through
X-ray emission in the ROSAT Deep Cluster Survey (RDCS). We find a temperature
of 3.7 +1.5 -0.9 keV and a bolometric luminosity of 8.2e43 +1.7e43 -1.6e43
erg/s for RDCS1317+2911, and a temperature of 4.9 +1.3 -0.9 keV and a
bolometric luminosity of 4.1e44 +0.5e44 -0.4e44 erg/s for RDCS1350+6007. Our
weak lensing analysis of RDCS1350+6007 confirms the general shape of the inner
density profile but predicts twice the mass of the model based on the X-ray
profile. We combine the X-ray luminosities and temperatures for RDCS clusters
of galaxies with such measurements of other clusters at high redshift (z>0.7)
and fit the luminosity-temperature relation. We find no statistically
significant evolution in the slope or zero-point of this relation at a median
of z=0.83. This result is in agreement with models of intracluster medium
evolution with significant pre-heating or high initial entropy values. We
discuss how low temperature, high redshift clusters of galaxies will allow us
to improve on this result and announce the discovery of two such objects, CXOU
J0910.1+5419 and CXOU J1316.9+2914.
