CuIn1-xGaxSe2 (CIGS) thin film has been successfully prepared by the one-step electrodeposition method, in which the faradaic and nonfaradaic processes occurred between the electrode and the electrolyte. Therefore, the investigation of the kinetic behavior of each metal ion is very important. In this study, we used the polarization curves to estimate the reduction potential of each metal ion and the reaction rate of the electrodeposition process. Electrochemical impedance spectroscopy technique has been used to investigate the electrochemical behavior of the interface between the electrode and the electrolyte. In this electrodeposition system, the influence of various deposition times, the concentration of Ga3+ on the charge transfer, electrical double layer, and charge-transfer resistance was also investigated. Experimental results show that the electrochemical kinetic behavior of the CIGS thin film is strongly influenced by the structure of the electrical double layer existing between the substrate and the electrolyte with different concentrations of Ga3+. With an increase in the electrodeposition time, the kinetic behavior of this electrodeposition system was gradually dominated by the diffusion process rather than the charge-transfer process. In this study, the carrier type of the CIGS thin film is of a p-type nature as confirmed by electrochemical measurement.