Oxidation-reduction potential (ORP) is an indicator of the oxidizing or reducing ability of a solution, and is measured by methods similar to those for

measuring pH.
ORPs are measured by using a pH meter with a millivoltmeter function in combination with a noble metal electrode (platinum or gold) and a reference electrode. ORPs are affected by temperature, and must be measured at a constant temperature (for example, at 25ºC).
We often hear people say that no matter how many times they hear explanations or read about ORP that they just don’t get it. This chapter explains ORPs in the simplest terms possible. Please stay with us.