Abstract: Various deposition techniques including filtration, spraying, dip-coating and self-assembly for depositing SWNT films on various substrates are developed. Different surfactants and SWNT sources have been tested, and the route for achieving films with high conductivity is developed. Transport studies on such films with randomly distributed SWNTs have been carried out. The density study of the conductivity of rare networks reveals two-dimensional percolation behavior. The temperature dependent reveals that tunneling between the SWNT-SWNT junctions is the governing mechanism for carriers transport. Frequency dependent (2 Hz-10 GHz) conductivity shows universal power law behavior for systems with randomly distributed barriers. Non-linear electrical field dependent conductivity at low temperature and room temperature reveals the barrier information of the SWNT-SWNT junctions. Transistors with rare SWNT network as the channel and thin SWNT films as the electrodes (source, drain and gate) are fabricated. Such all-nanotube transistors are potentially useful for stretchable electronic applications due to the excellent mechanical properties of nanotube networks. Also, transistors using pyrenecyclodextrin-coated SWNTs as the channel material are used for sensing specific organic molecules. Thin SWNT films show low sheet resistance and high optical transmittance. Films with 120 ohm/sq with 80% transparency at 550 nm fabricated and routes for improving the performance are proposed. Optoelectronic, mechanical and chemical properties are studied. Two Patterning techniques are developed: PDMS stamping and lithography with plasma etching. Chapter 6 describes the device applications of the transparent SWNT electrodes: as anodes for organic solar cells, displays, as stretchable electrodes for actuator, and as microwave shielding materials. Other applications of this novel electrode are proposed and the issues of the device applications are discussed. Light-sensitive CdSe-SWNT hybrids are synthesized and efficient charge transfer in the hybrids is studied using SWNT network transistors. Using such hybrids for organic solar cell application is discussed. At the end, composites incorporating SWNTs are studied: SWNT-PEDOT composite, conducting fabric and bio-composites as electrodes for fuel cell applications.