The hydrochlorides of a-aminoacid esters react with Au2Cl6 in thionyl chloride to give the ammonium salts [H3NCHRCO2R′]+AuCl4 - (R = H , Me, R′ = H , Me, Et). The X-ray structure of [H3NCH(Me)CO2Me]+AuCl4 - has been determined. The reactions of a-aminoacids with Au2Cl6 in SOCl2 afford mixtures of ammonium tetrachloroaurate(III) salts with a-amino acids, a-amino acid chlorides or a-amino acid anhydrides as amine components. Cysteine esters reduce gold(III) to give the gold(I) compounds [AuSCH2CH(N H2)CO2R]n (R = Me, Et).