o design a new bioelectrochemical method to detect Nitrite (NO2-) and hydroxylamine (NH2OH) employing Hydroxylamine oxidase (HAO) and modified electrode by Zirconia Nanoparticles (ZrO2 NPs) we benefited the bioelectrochemical methods. The morphological studies of Zirconia Nanoparticles were carried out by atomic force microscope (AFM), transmission electron microscope (TEM), X-ray diffraction (XRD) and TU-1901 double-beam UV-visible spectrophotometer (UV-VIS). Electrochemical studies were done by cyclic voltammetry (CV) method. The formal potential (E0) for the HAO redox reaction on the HAO / ZrO2 NPs/ carbon paste electrode (CPE) was 250 mV with respect to the reference electrode (SCE). The final results show the linear dependence of the anodic peak current on the NO2- concentration in the range of 3 to 117 uM. The stability of HAO / ZrO2 NPs/CPE electrode biosensor has been checked by carrying out the experiments at the regular interval of a week and it has been found that HAO / ZrO2 NPs/CPE electrode based biosensor retains its 87% activity after 21 days.