ROSAT Position Sensitive Proportional Counter (PSPC) observations of the double-lobed radio source 3C 390.3 show resolved X-ray emission spatially located at the position of the northern radio hotspot. Possible origins for this X-ray emission are discussed. It is found that neither thermal emission nor inverse Compton emission could account for the observed X-rays if particle-field equipartition conditions must prevail. Alternatively, the available multifrequency data from the northern hotspot are consistent with a smoothly decaying synchrotron spectrum from the radio to the X-ray frequencies. In such case, the shape of the synchrotron spectrum is similar to those seen in the western hotspots of Pictor A and 3C 303.