In this study, Pd@CeO 2 -SnO 2 nanocomposite was synthesized and various methods such as field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, fourier-transform infrared spectroscopy, X-ray diffraction, and elemental mapping were used to characterization and investigation the structure of the nanocomposite. Then the glassy carbon electrodes and rotating disk electrode were modified with the mentioned nanocomposite. At first, the electrochemical behavior of sensor was investigated by cyclic voltammetry technique; then, the chronoamperometric method was used to determination of hydrogen peroxide and nitrite. Hydrogen peroxide measurements were performed at pHs 7.0 and 8.0. For the H 2 O 2 reduction reaction at pH=7.0, the linear range and detection limit were obtained as 0.15-1920 ?M and 44.0 nM, respectively. Also, at pH=8.0, the linear range and detection limit were obtained as 0.12-2170 ?M and 36.0 nM, respectively. In addition, for the nitrite oxidation reaction at pH=6.0, the linear range and detection limit was calculated as 0.36-2200 ?M and 0.10 ?M, respectively. In the following, the sensor response to the determination of analytes was studied in the presence of various types of potential interference species. The results confirmed the high selectivity of the designed sensor for the determination of H 2 O 2 and NO 2 - . Finally, In order to investigation the practical application of the sensor in determination of hydrogen peroxide, three different milk samples; and in the determination of nitrite, various samples such as sausages, salami, cheese, onions, potatoes and water were studied. Comparing the results of the proposed method with standard methods, it can be seen that the designed sensor has very high ability in the determination of trace amounts of hydrogen peroxide and nitrite in the real samples.