A monochloramine microsensor includes an elongated housing defining a central axis and an open interior and having a capillary opening at one end. A semi-permeable membrane covers the capillary opening, the semi-permeable membrane allowing diffusion of chloramines there-through while preventing water from entering into the interior of the housing. A chloramine sensitive element in the form of a wire, fiber or nanotube is mounted within the housing, the chloramine sensitive element, when used in conjunction with an anode, outputs current in an amount proportional to the concentration of chloramine present in a liquid sample in which the chloramine sensitive element is immersed. The chloramine sensitive element extends along a length of the central axis to a first end adjacent to and spaced from the semi-permeable membrane. The chloramine sensitive element is a gold wire, a platinum wire, a carbon fiber or a carbon nanotube.