Water hyacinth is a bioindicator plant that has high tolerance to metal pollutans concentration of Cr(III) and Cr(VI) metal ions species in Ogan river. Measurement of Cr(III) and Cr(VI) metal ions species has done using the concentration cell potentiometric method. This study aims to validated the method (linearity, precision, accuracy, LoD & LoQ). Applying the concentration cell potentiometric…