1. A conductometric study of the reaction of hydrogen with granular films of Pd/6% Ru alloy has confirmed the presence of an α-Β transformation in the alloy-hydrogen system at 303‡K and PH2=20-30 torr. 2. Under all the conditions studied, reversibly and stably adsorbed cyclohexane particles are principally polarized negatively. 3. Stably adsorbed particles of n-hexane are weakly polarized. The polarization of reversibly adsorbed n-hexane changes from positive for the α-phase to negative for the Β-hydride phase of the alloy-hydrogen system. 4. The effect of hydrogen on the reversible adsorption of the hydrocarbons studied on the a-phase of the alloy-hydrogen system is associated with the reaction in the surface layer of polarized particles of hydrocarbons with a positively polarized form of the adsorbed hydrogen. © 1985 Plenum Publishing Corporation.