This paper reports the generation in situ of Ni-0 nanoparticles and thin films by focusing a TEM electron beam over NiO/ZrO2-CeO2 and NiO. Electron irradiation was carried out using a TEM at 80 and 100 kV, concentrated over individual NiO/ZrO2-CeO2 and NiO agglomerates. The results showed that just after electron irradiation started, the reduction of NiO phase occurred and fine Ni-0 nanoparticles were formed. These Ni nanoparticles were limited to a small area around the irradiated NiO/ZrO2-CeO2 and NiO agglomerates. It was found that the nanoparticles growth increased with irradiation time, and a Ni-0 thin film was formed after 50 min. The evolution was studied using BF images and SAD patterns. Characterization of single nanoparticles was conducted using HRTEM, STEM and EDS. (C) 2013 Elsevier B.V. All rights reserved.