Using XMM we detect faint unresolved X-ray emission from the Compact Steep Spectrum radio galaxy 3CÂ 303.1 .
We detect a thermal component at kT \simeq 0.8 keV which seems likely to be produced in the ISM of the host galaxy .
There is evidence for a second component in the spectrum whose nature is currently ambiguous .
Plausible hypotheses for the second component include ( 1 ) hot gas shocked by the expansion of the radio source , and ( 2 ) Synchrotron self-Compton emission from the southern radio lobe if the magnetic field is below the equipartition value by a factor of \sim 3.5 .