This work presents an analysis of the kinetics and mechanism of electrode reactions taking place during polarization of an Au polycrystalline electrode in the solution containing aqua- and aquachloro- complexes of palladium(II). Stability range of [PdClx(H2O)(4-x)](2-x)(x = 3,4) was defined from the thermodynamic analysis of the electrolyte. Spectrophotometric measurements were applied for stability tests of complexes present in the electrolyte. Besides classical electrochemical tests, electrogravimetric tests were also performed. Determined values of Mix demonstrated that a metallic Pd deposit is formed as a result of a 2-electron reduction reaction of Pd(II) complexes. A deposition started from potential of similar to 0.5 V. Initially M/z values suggest a coarse palladium(II) complexes adsorption. All the examined electrode reactions of [PdClx(H2O)(4-x)](2-x)(x = 3,4) took place within the overpotential range and were diffusion controlled. Diffusion coefficient of [PdClx(H2O)(4-x)](2-x) (x = 3,4) was determined with the use of Berzins - Delahay equation. Cyclic voltammograms (CV) indicated also reactions of hydrogen adsorption and absorption by Pd deposit formed during cathodic sweep. (C) 2013 The Electrochemical Society. All rights reserved.