Display omitted •A flow-cell-based electrochemical analyzer was developed.•It enabled the fast determination of additive concentrations in a Cu plating bath.•Linear interpolation was used to analyze the concentrations.•The isotherm-based plotting provided better linearity with higher R2 values. Automatic Cu plating bath analyzers are required for the long-term maintenance of the bath quality in the semiconductor and printed circuit board industries. This study reports the development of a flow cell-based electrochemical analyzer for the simple and fast determination of additive concentrations in a Cu plating bath. To determine the additive concentrations, cyclic voltammetry was sequentially performed using a flow cell system for the following solutions: blank, blank + sample, and two references. The stripping charges for each solution were obtained. The concentrations of the additives in the target solution were determined by the linear interpolation of the stripping charge between the two references. To improve the determination accuracy, the stripping charges were reprocessed based on adsorption isotherms. The proposed approach enables the fast and highly accurate determination of organic additives in a Cu electroplating solution.