Silver oxide (AgOx) thin films were found to exhibit localized surface plasmon resonance absorption when they were heated above the decomposition temperature. The resonance absorption for annealed AgO was obvious with the film thickness of 5 nm, and it became weak at 15 nm. Atomic force microscope images of a 15 nm film have shown that various-size particles (diameter in lateral direction:, 100-600, nm) are dispersed after annealing at 600 degreesC. Similar optical and morphological properties were obtained with the oxygen composition ratio in the range of 33-48 at. % (i.e., Ag2O and AgO). AgOx film with about 15 nm thickness is mostly used in super-resolutional near-field structure (super-RENS) when combined with an optical disk for the readout of small marks beyond the diffraction limit. The results did not show, however, any evidence that,the absorption properties and the readout process of super-RENS disk are well correlated. (C) 2003 American Vacuum Society.