Arunkumar Gunasekaran you have not given much details of your experiment, electrode arrangement and electrochemical technique, but you should check the distance of your reference electrode, as well as the conductivity of the solution, also the sweep speed in case of CV. Because these are factors that can lead to a high iR drop. If you have the working and reference electrodes at a large distance, then the iR drop can be significant, same as at low conductivity and and very high sweep speed.