In this work, we report fabrication of highly porous metal-oxide nanostructures by pulsed laser deposition performed in air at atmospheric pressure. The attention was focused on the structure, morphology, and composition of ZnO, TiO2, SnO2 and MoO3 metal oxides. The technology applied leads to formation of nanostructures composed by nanoparticles. Additionally, a nanocomposite sample consisting of metal-oxide and noble-metal nanoparticles was fabricated. The nanostructures were produced in view of applications as gas sensors. Preliminary results on the gas-sensing properties of the metal-oxide nanostructures are reported.