The modification of electrode surfaces with different metallorganic compounds ensures their application in electrocatalysis as photoelectrochemical devices and analytical sensors [1]. Recent research on development of new electrode materials is directly connected with the use of macrocyclic complexes of some transition metals in the form of polymeric redox-active assemblies. Complexes of transition metals with Salen ligands can be electropolymerized on electrode surface leading to conductive polymers. As the fabricated materials possess a wide spectrum of clear-cut intrinsic properties, they can be used in several research areas. Due to their monomer properties, the palladium(II)-based polymers can be quite attractive for using in electrocatalysis and in photoelectrochemical devices. To characterise these polymers several studies have been carried out with the use of cyclic voltammetry and electrical impedance analysis. However, the mechanisms of polymerization and redox switching are still under discussion [2]. Here, we report the results of EPR spectroscopy at room temperature and 77 K obtained for polymeric films based on palladium(II) with Salen and SaltMe complexes. This technique is an important tool for the complete characterization of the oxidized state to give information about the nature of the redox couple involved and distinguish between ligand and metal based oxidation processes. EPR spectra of poly[Pd(Salen)] and poly[Pd(saltMe)] in the oxidized state are very similar, and show a single isotropic signal with g factor of 2.004 and 2.006 respectively at room temperature and 77K; no hyperfine splittings were observed. All the spectra are of a radical type, thus indicating that polymerization and redox switching of Pd(II)-organic polymers involve ligand-based oxidative processes. Furthermore, as the intensity of the EPR signal depends on the applied potential, we can conclude that the main charge carriers are polarons.