The hydrothermal method synthesized the first cobalt ferrite and cobalt oxide nanoparticles in this article. The synthesized nanoparticles were then subjected to various analyzes such as X-ray diffraction patterns, scanning electron microscopy images, infrared spectroscopy, and vibration sample magnetometer to ensure their properties and prepare the nanoparticles for the next step. Then, 6% by weight of nanoparticles were added to the epoxy resin as a reinforce, and a polymer matrix composite was made. After making the composites according to the ASTM D638 standard, they were subjected to a tensile test. The results showed that the nanoparticles were prepared very fine, uniform, high purity, and had good magnetic properties. Also, hydrothermal was a suitable method for the synthesis of these nanoparticles. Furthermore, samples made using cobalt ferrite nanoparticles offer better tensile properties than samples made with cobalt oxide. However, in general, the tensile properties of composites have improved compared to pure polymers. پرونده مقاله