Sensor technology has drawn a tremendous amount of attention because of its ability to provide fast feedback on the environment. This has led to intensive research activities worldwide to develop new sensing materials and technologies. With the advancement in nanotechnology, miniaturized sensors with reduced weight, lower power consumption, and low cost can be realized. In order to realize this potential, it is critical to develop reliable growth techniques capable of producing high purity, density and desired properties of the sensing element. This article focuses on the production of good quality sensing elements in the form of nanotubes; carbon nanotubes (CNTs) and titania nanotubes. Both types of CNTs, single-walled (SWCNT) and multiwalled (MWCNT) grown in the form of vertically aligned film on the substrates are believed to have enhanced sensing properties because of their high purity and directionality. Similarly with titania nanotubes, their sensitivity and selectivity towards hydrogen would be greatly increased because of their quality. Based on the changes in the specific properties of these nanotubes, chemical sensors can then be developed. ©2007 IEEE.