Abstract: A device for applying marking symbols to an animal's hide, a piece of meat's surface and like protein-containing tissue by locally dielectrically heating the tissue using high frequency electromagnetic energy to thereby dissect the protein structure and produce a mark having a different color than the surrounding tissue. The device comprises a stamping member including a metal symbol electrode having a protruding portion which is applied in use to the protein-containing tissue and an electrically insulating holder, such as a refractory material, in which the electrode is protrudingly mounted; a high frequency generator having a frequency range of from 2 to 22 MHz, most preferably from 2 to 4 MHz, and an output power of from 20 to 1000 Watts; and preferably a switching means for selectively establishing electrical connector between the stamping member and the high frequency generator to thereby send electromagnetic energy into the tissue upon which the protruding portion of the electrode is applied.