The praseodymium oxide (PrxOy) and praseodymium-doped vanadium oxide films were synthesized onto the ITO electrode by electrolysis in molten dimethylsulphone (DMSO2)-PrCl3, DMSO2-PrCl3-LiNO3 and DMSO2-PrCl3-V2O5 system at the temperature about 150 degreesC. The obtained films were characterized by X-ray diffraction (XRD) and spectroscopic measurements. Moreover, the electrochromic (EC) reactions of the oxide films in solution of propylene carbonate (PC) were investigated. The absorption spectrum of praseodyiniurn oxide films obtained by electrodeposition in DMSO2-PrCl3 Systems had 560- and 390-nm peaks due to mixed valence of Pr3+ and Pr2+. And the effect of lithium ion intercalation or deintercalation was shown in color change of oxide films. The cyclic voltammograms (CV) of praseodymium-doped vanadium oxide films obtained by electrodeposition in DMSO2-PrCl3-V2O5 systems showed the good reversibility of EC reactions.