Open Circuit Potential (OCP) is one of the electrochemical methods to evaluate the corrosion performance of organic coatings. Some authors have used OCP measurement data to confirm their results obtained with Electrochemical Impedance Spectroscopy (EIS). In this investigation, there is an attempt to utilize OCP measurements to estimate the CPVC (Critical Pigment Volume Concentration) of two anti-corrosive pigments, i.e., zinc phosphate and zinc chromate. OCP measurements showed two distinct behaviors in the PVCs lower than CPVC and one typical behavior at the PVCs higher than CPVC. The results showed that OCP measurement could be a highly reliable method for the evaluation of CPVC.