Nanoporous GaN films were prepared by UV-assisted electrochemical etching. It was observed that by employing rapid thermal annealing (RTA), optical properties of porous GaN films could be considerably improved. The nanoporous GaN films were subjected to RTA within the temperature range of 500-1100 degrees C under nitrogen and oxygen ambient. The band-edge photoluminescence (PL) intensity from the porous GaN films showed a monotonic increase with the annealing temperature up to 1000 degrees C in N-2. However, the band-edge PL intensity showed a drastic reduction for the porous samples annealed under oxygen ambient. Besides this, investigation of the effects of annealing conditions on Eu-implanted nanoporous GaN in N-2 and O-2 ambient was also carried out. We have observed that annealing in N-2 significantly enhances the Eu-related red luminescence around 621 nm, which implies that annealing conditions could play an influential role for light extraction from nanostructured GaN surfaces. (c) 2006 The Electrochemical Society.