Volatile metals and metalloids were sampled from hot springs, fumaroles, and a hydrothermally influenced wetland in Yellowstone National Park. The sampling was based on diffusion through gas sampling chambers. Collected gases were stabilized by dissolution and oxidation in 1:100 diluted NaOCl. Special procedures were developed to analyze the oxidized samples by GF-AAS and HG-AAS. For ICP-MS, samples had to be blank-corrected for polyatomic isotope interferences, especially by 23Na35Cl+ and 23Na37Cl+ on 58Ni and 60Ni and by 40Ar23Na+ on 63Cu. From the concentrations trapped in solution, net diffusion rates were calculated by Fick's first law. The highest concentrations reached a maximum of 8 g/m3 for volatile silicon. Volatile nickel, tungsten, zinc, copper, and molybdenum, previously only known from anthropogenic sources, occurred naturally in the hydrothermal gases in ranges of tens to hundreds of microg/m3. Replicate measurements indicated significant temporal variations in concentrations, probably the result of complex changes in the hydrothermal regime as well as varying microbial activity. Global correlations between gaseous and superficial aqueous phases were missing.