Copper monodispersed nanoparticles (2-5 nm) embedded into submicron particles of sepiolite (Mg8Si12O30(OH)(4)(H2O)(4)center dot 8H(2)O), suitable to be used for biological applications have been obtained after a specific treatment and subsequent reduction process. Cu/Sepiolite particles have revealed as a strong bactericide (similar to Triclosan) so that they were able to decrease the starting microorganism concentrations of Staphylococcus aureus or Escherichia coli by 99.9%.