A new chemosensor has been used to monitor atmospheric nitrogen oxides [NO + NO2] at ppb level. It is based on the catalytic reaction of nitrogen oxides with rhodamine B hydrazide to produce a colored compound through the hydrolysis of the amide bond of rhodamine B hydrazide. A simple spectrophotometer has been be used to monitor atmospheric nitrogen dioxide continuously at ppb level. The air samples were purged through the sampling cuvette containing rhodamine B hydrazide using peristaltic pump. The proposed method has been successfully applied to monitor the ambient nitrogen dioxide levels at traffic junction points within the city limits and the results obtained are in good agreement with the standard Griess-Ilsovey method. Key words: rhodamine B hydrazide, nitrogen dioxide, amide bond,