The present invention relates to nano-structured silver oxide film based voltammetric sensors for pesticides, for example, endosulfan or atrazine or methyl parathion in natural waters which are highly sensitive, reliable, precise, stable and regenerable. The process of which is as follows: i) Electrochemical conditioning of polycrystalline silver electrode by potentiostating at 0.32 V Vs Ag/AgCl for 15 min. in 1M NaOH + 5x10-5M Na2HPO4 solution. ii) Formation of nano-structured silver oxide film by repeated potentiodynamic cycling (7-9 cycles) in the potential range -0.3 to + 0.5 V vs Ag/AgCl. iii) Voltammetric transducer based electrochemical sensing in NaOH -Na2HPO4 sample media. The designed sensor is cut above the hither to reported sensors in terms of sensitivity, precision and in offering wider calibration range. The developed sensor can find wide spread use in environmental screening & monitoring, chemical industry, clinical diagnostics and other related fields for selected pesticides.