This Bachelor’s project studied the eco-friendly synthesis of two different metallic nanoparticles (NP): silver (Ag) and copper (Cu) by using a green production route; mainly based on the grape stalk’s extract in order to reproduce the production costs and make the final process more eco-friendly. Within this context, the influence of temperature during the reaction change of NPs’ solution over time for both synthesized NPs were characterized by means of advanced characterization techniques, like UV/Vis spectroscopy, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX) techniques. The changes of reduction potential of reagents during the storage have been observed. It’s possible to synthesize NPs in room temperature; however, the concentration of metallic ion dissolution affects the NPs’ size and it’s the main variable to decide of the synthesis will take place or not.