The invention provides a reagent suitable for the dissolution of metallic gold and various methods for the application of the reagent including gold analysis, gold extraction, gold separation and the in-situ treatment of gold deposits.The reagent uses a protic solvent containing a preferably non-reducing cation source and a source of bromine optionally in combination with a strong oxidizing agent. The protic solvent is water or a lower alkyl alcohol or a mixture thereof. The cation source preferably highly dissociates in the protic solvent and suitable cation sources include dibasic ammonium phosphate, ammonium sulphate, potassium chromate, hydrochloric acid, sodium hydroxide and potassium hydroxide. Cation sources which liberate ammonium cations are preferred.The strong oxidizing agent should by highly dissociated in the solvent and is preferably selected from the group consisting of hydrogen peroxide, sodium peroxide, potassium peroxide, sodium permanganate, potassium permanganate, potassium dichromate and ferric sulphate.