We report the discovery of a small H α nebula positionally coincident with the candidate neutron star AX J0851.9-4617.4 located at the center of the supernova remnant G 266.2-1.2. The nebula has a roughly circular shape with a diameter of ~6 '' and a flux of ~10 -2 photons cm -2 s -1 in the H α line. Considering the uncertainties in the distance and energy output from the putative neutron star, we find that such a flux can be explained either in a bow-shock model or assuming that the nebular emission is due to photo-ionization and heating of the ambient gas.