A low melting point soda-lime glass powder containing copper nanoparticles with high antibacterial (against gram-positive and gram-negative bacteria) and antifungal activity has been obtained. Sepiolite fibres containing monodispersed copper nanoparticles (d50≈30 ± 5 nm) were used as the source of the copper nanoparticles. The observed high activity of the obtained glass powder, particularly against yeast, has been explained by considering the inhibitory synergistic effect of the Ca2+ lixiviated from the glass on the growth of the colonies.