During the last decade the X-ray observations ROSAT and ASCA have made it possible to distinguish between photospheric (thermal) and (nonthermal) magnetospheric radiation of single neutron stars. The next generation of X-ray satellites (Chandra, XMM and Astro-E) and the follow-up mission Constellation and XEUS- will allow spectroscopic and timing studies with much higher sensitivity and resolution. Primary future goals are to determine the chemical composition of neutron star photospheres and to measure the gravitational redshift of spectral features.