[en] In the present study, silver and copper nanoparticles were synthesized by using chemical reduction method. TGA was used to know the thermal stability and it was found that silver nanoparticles were more stable than copper nanoparticles. It was also observed from thermogram that copper nanoparticles gained small weight at 450 °C due to oxidation. DSC curves showed the peaks of endothermic and exothermic reactions that indicated the chemical changes inside nanoparticles. RD peaks demonstrated the face centered cubic crystal structure with crystallite size 15.13 nm and 14.45 nm of silver and copper nanoparticles, respectively. XRD also showed the partial oxidation of copper nanoparticles (Cu₂O). Spherical morphology with average grain size ranging 120–300 nm of silver nanoparticles and 150–350 nm of copper nanoparticles was observed by SEM. It was found that silver and copper nanoparticles are significant antibacterial agent against common human pathogenic bacteria like Staphylococcus aureus and Escherichia coli. It was observed that antibacterial activity increased as concentration of samples increased. Maximum zone of inhibition was observed by silver nanoparticles at concentration 0.24 g ml⁻¹. Copper nanoparticles results were comparable with silver nanoparticles against S. aureus but showed slightly less antibacterial action against E. coli. It was observed that silver nanoparticles were more reactive to inhibit the growth of bacteria as compared to copper nanoparticles. (paper)