Copper nanoparticles in a silica matrix are prepared by a three-step procedure. In the first step a copper salt is reacted with an alkoxysilane of the type (RO)₃Si(CH₂)_nA, where A is a coordinating organic group. The obtained metal complexes {[(RO)₃Si(CH₂)_nA]_xCu]²⁺ are used as precursors for sol-gel processing, with Si(OR)₄ as co-reactant to adjust the metal:silica ratio. In the second step, the metal complex-containing gels are calcined in air at high temperatures, and metal oxide nanoparticles in a silica matrix are formed. Finally, the metal oxide nanoparticles are reduced to metal nanoparticles.