The pressure-composition isotherms for oxygen in PrBa2Cu3O6+x were measured by means of coulometric titration in the temperature range 550-825 degrees C and at oxygen pressures between 10(-3) and 1 atm. The composition dependences of thermodynamic potentials reveal substantially non-ideal behavior of the ensemble of the oxygen ions in the basal plane. The oxygen ion conductivity of the PrBa2Cu3O6+x compound was measured by a permeation technique in the temperature range 600-850 degrees C and at oxygen pressures between 0.08 and 1.00 atm. The data were employed for calculation of the oxygen chemical diffusion coefficient. The activation energy of the oxygen conductivity and oxygen diffusivity was found to depend linearly on the oxygen content, U = 2.46-1.57x (eV), in the integral 0.35 < x < 0.60 which was explained by interaction of movable oxygen ions.