Internal friction behavior of hydrogen in vanadium-niobium alloys containing from 40 at. pct. niobium to 100 at. pct. niobium as a function of hydrogen concentration was investigated. The internal friction measurements were performed in an electrostatic drive and detection apparatus for rods in flexural vibration in the temperature range from 30°K to 290°K;An internal friction peak due to hydrogen was found in all the vanadium-niobium alloys. The peak was considered to be due to the jumps of hydrogen atoms in solid solution. The peak moved toward lower temperatures with increasing hydrogen concentration. In other words, the activation energies of the hydrogen motion responsible for the internal friction peaks decreased with increasing hydrogen concentration. The activation energies increased with increasing niobium concentration up to 75 at. pct. niobium then decreased. The peaks were broader than expected for single Debye peaks. The broad peaks were considered to be due to superposition of many single Debye peaks with different activation energies and the distribution of activation energies were estimated by the Direct Spectrum Analysis. The activation energies and [tau][subscript] o values for the hydrogen internal friction processes obtained from the present study were compared to those obtained from long range diffusion experiments;In order to examine the isotope effect, internal friction of deuterium in the same alloys were measured and compared to those of hydrogen. Effects of oxygen on the internal friction behavior of hydrogen and deuterium were also investigated.