The potentiometric response behavior of a polypyrrole(PPy) coated Pt electrode to nitrate ion has been studied. The electrode shows a nernstian behavior with a slope of 59 mV over 0.50 M to $1.0{ imes}10^{-3}M;NO_3;^-$ and a detection limit of $1.0{ imes}10^{-4}M;NO_3;^-$. The response of the electrode is fast and the selectivities for $I^-,;ClO_4;^-,;and;IO_4;^-$ are found to be improved. The effect of pH on the potential response to $NO_3;^-$ is compared with the existing nitrate ion selective electrodes.