In this talk the various uses of one-dimensional (1D) nanostructures such as nanorods and nanotubes in gas sensing applications will be reviewed. During recent years semiconducting metal oxide ZnO one-dimensional (1D) nanostructures have been popular because the high surface area- to-volume ratio of these nanostructures is potentially useful for gas sensing applications. ZnO is characterized by a wide band gape of 3.37 eV and a large exciton binding energy (~60 meV). The use of 1-D ZnO nanostructures is attractive due to the availability of low cost synthesis processes and a reasonably good electrical conductivity that can be further modulated and improved by doping with Al to achieve Al doped ZnO (AZO). In general, ZnO 1-D nanorod structures can be successfully synthesized by hydrothermal method in an autoclave with ZnO seed layers deposited on the substrate. The solutions used for ZnO nanorods hydrothermal growth are typically composed of zinc nitrate hexahydrate (Zn(NO₃)6H₂O) and hexamethylenetetramine ((CH₂)₆N₄) dissolved in DI water. The introduction of 3-D wrap-around coatings with ALD technology enabled recently the fabrication of nested ZnO nanotubes with alternate coatings of Al2O3 and ZnO to synthesize AZO coatings. In order to increase the critical surface-to-volume ratio even further the state-of-the-art was further expanded to include sacrificial ALD alumina coatings that can subsequently be selectively removed by wet chemical means using a Sodium hydroxide (NaOH) etch solution. Such an integrated process sequence produces empty annular rings surrounding the core ZnO nanorod, thereby exposing additional free surfaces of AZO and ZnO for catalytic sensing reactions. In principle several or ultimately n sacrificial coating layers can be added by ALD technology to fabricate coaxial multiple nested nanotube structures with one nanotube inside the other. Each empty sacrificial annular ring adds two additional free reactive surfaces to the sensor. The application potential for MOS gas sensors and photodetectors with 1-D ZnO nanostructures will be reviewed. The physical characterization and sensing performances of ZnO nanorods benchmarked against ZnO multiple nested nanotube structures with AZO coatings and sacrificial layers will be discussed and compared to literature examples.