Silver nanoparticles (AgNPs) embedded within polymethacrylic-acid (PMA) matrix were prepared by a simple chemical route. The obtained AgNPs@PMA composite sample was characterized by means of UV-Vis spectroscopy, SEM, TEM, XPS and used as electrodic material for electrochemical sensors. The electrocatalytic properties of a fabricated AgNPs@PMA/CNTs-modified electrode was investigated by cyclic voltammetry. A voltammetric sensor based on a disposable carbon electrode modified by AgNPs@PMA/CNTs composites has been developed for nitrate monitoring in water at neutral pH.