In this contribution, the use of novel nanocoatings composed of single-walled carbon nanotubes (SWCNTs) embedded in Cadmium Arachidate (CdA) matrixes is proposed to improve the typical low adhesion of carbon nanotubes to the surface of standard optical fibers [1], thus enabling the development of highly sensitive, reliable and robust SWCNT-based fiber optic chemo-sensors. In particular, the sensing performance of optical chemo-sensors coated by such SWCNT nanocomposites have been here assessed against several chemicals both in air and water environments, at room temperature. The nanocomposite sensing layers have been transferred upon the distal end of standard optical fibers by the Langmuir-Blodgett technique. Single wavelength reflectance measurements (λ=1310 nm) have been carried out to monitor chemical concentration through changes in the refractive index and thickness of the nanocoatings induced by its interaction with the molecules of target analytes. The experimental evidences demonstrate that such nanoscale overlays integrated with the optical fiber technology offers great potentialities for the room temperature detection of chemicals either in air or water environments and could lead to significant improvements of the traditional optoelectronic sensors based on SWCNTs layers. © 2008 IEEE.