The calculation of averaged thermal diffusion coefficients and absorption cross sections for hydrogenous assemblies is discussed, and numerical results are presented. Comparison is made with available experimental information. The averages are taken over Wigner-Wilkins spectra, which assume moderation by a perfect gas of hydrogen atoms in the presence of a 1/v absorber. The Radkowsky prescription has been used to obtain transport cross sections for various compounds containing hydrogen. Power series expansions are presented which simplify the calculation of average diffusion coefficients for mixtures.