Abstract: The adsorption isotherms of H₂PdCl₄ and 6 competitive adsorbates, acetic, propionic butyric, malonic, citric and maleic acids on Al₂O₃ have been investigated. They are all fiffed in with the langmuir adsorption isotherm. The results indicated that the impregnation kinetics of H₂PdCl₄ on Al₂O₃ was effected by the pH value of impregnation solution and the competitive adsorbates. Addition of competitive adsorbates was able to chauge the UV absorption spectrum of H₂PdCl₄ solution. It is suggested that there should be an interaction between H₂PdCl₄ and competitive adsorbates.