Abstract: An electrochemical scale detection and control system, for on-line detection and control of nucleation and growth of inorganic scales. The system comprises sensitive microprocessor controlled electrochemical monitoring instrumentation for detecting electrochemical changes which occur as a consequence of scale nucleation, growth and removal, with subsequent processing to provide means of controlling scale inhibitor additions. The device takes measurements continuously and provides uninterrupted output of the scaling tendency. A three-element measurement probe consisting of material having little propensity for corrosion in the scaling medium of interest is used as the scale sensor.