Isolated neutron stars, in particular, those exhibiting reduced magnetospheric activity, are unique laboratories for testing radiative properties of neutron star surfaces, high gravity and high magnetic field physics. These objects could eventually bring important constraints on the debated equation of state of matter in neutron star interior.
Thanks to the large collecting power and good energy resolution of the XMM-Newton instruments, detailed X-ray spectral analysis can now be performed in the 0.2 to 12 keV energy range. In addition, the availability of VLTs offers the possibility to study their optical emission and detect their proper motion from the ground.
I will review recent X-ray and optical observational results and will discuss current issues on the emission mechanisms and population properties of isolated neutron stars.