Nanoporous gold (NPG) layers have been fabricated by silver leaching of Ag-Au alloys with different dealloying processes and working temperatures. Structural, compositional and optical properties of the different samples have been analyzed with several experimental techniques: scanning and transmission electron microscopy (SEM/TEM), electrochemical impedance spectroscopy (EIS), Rutherford back scattering (RBS), spectroscopic ellipsometry. A periodic pattern has been realized on samples surface with focused ion beam (FIB) lithography in order to exploit NPG metallic behavior for surface plasmon polaritons (SPPs) excitation. The plasmonic response of the several NPG gratings has been analyzed and related to structural properties and fabrication conditions.