We report on the XMM-Newton observations of the 143 ms pulsar PSR J0538+2817 .
We present evidence for the first detections of pulsed X-rays from the source at a frequency which is consistent with the predicted radio frequency .
The pulse profile is broad and asymmetric , with a pulse fraction of 18 \pm 3 % .
We find that the spectrum of the source is well-fit with a blackbody with T ^ { \infty } = ( 2.12 ^ { +0.04 } _ { -0.03 } ) \times 10 ^ { 6 } K and N _ { H } = 2.5 \times 10 ^ { 21 } cm ^ { -2 } .
The radius determined from the model fit of 1.68 \pm 0.05 km suggests that the emission is from a heated polar cap .
A fit to the spectrum with an atmospheric model reduces the inferred temperature and hence increases the radius of the emitting region , however the pulsar distance determined from the fit is then smaller than the dispersion distance .