Abstract: An apparatus and method are disclosed for the measurement of hydrogen peroxide concentration from within a textile bleaching bath. The apparatus comprising a sample chamber, a process valve between a source of the solution to be tested and the sample chamber, a reagent valve between a source of reagent and the sample chamber, a pressure measurement tube attached to and extending from the sample chamber, an exhaust valve in communication with the sample chamber, and a pump at a location between the exhaust valve and exhaust device. The process measures hydrogen peroxide concentration by the pressure of the oxygen given off into a known volume as a result of a chemical reaction between the hydrogen peroxide and sodium hypochlorite.