A chloramine amperometric sensor (14, 20) includes a sensor body (22) with an electrolyte (24) disposed inside the sensor body (22). A membrane (32) is coupled to the sensor body (22) and adapted to pass chloramine therethrough. A reference electrode (30) is disposed in the electrolyte (24) and coupled to a first conductor (36). A second conductor (34) is coupled to a working electrode (26) that is disposed proximate the membrane (32). The working electrode (26) is constructed from a noble metal in non-compact form. The non-compact form can be a Gas Diffusion Electrode, which can include metal mesh, carbon paper, carbon cloth, metal/carbon powder loaded on a porous membrane or any combination thereof.