A method for chemically modifying a surface of a metallic substrate material being made of a first metallic material includes the steps of a) bonding an alloy material made of the first metallic material and a second metallic material onto the substrate material; and b) etching away at least some of the first metallic material from the bonded substrate material to obtain a modified substrate material, wherein the modified substrate material has an increased specific surface area. A substrate for Surface Enhanced Raman Spectroscopy (SERS) includes a modified substrate material.