The interface problems in nanomaterial based electronics play important roles. We have learned that the nanocontact, due to its reduced contact area, could give a high electrical contact resistance and a nonlinear current-voltage behavior though the specific contact resistance is in the same order of magnitude as that of macroscopic contacts. Through the current-voltage and temperature behaviors, the nanocontact properties could be categorized into Ohmic and Schottky types. The electrical properties of the nanowire based two-probe devices could be rationalized as two Ohmic contacts, one Ohmic and one Schottky contacts, and two back-to-back Schottky contacts. Moreover, the nanocontact could be treated as a one-dimensional disordered electron system for further studies. After the intrinsic nanowire and contact resistances are separated from each other, the electron transport and the carrier concentration of native doping in ZnO and InP nanowires can be determined. The nanowires are determined to have low carrier concentrations, implying a high sensitivity to light and gas. The contact and nanowire dominated two-probe devices are exposed to light and gas to identify the contact effects. In addition to the inorganic nanowires, the organic nanomaterials, the HCl-doped polyaniline nanofibers, can be analyzed by using the same approach. The dielectrophoresis technique is implemented to position nanofibers into an electron-beam lithographically patterned nanogap. To shine the electron-beam on contact areas, the organic/inorganic nanocontact resistance is reduced so as to probe the intrinsic electrical property of a single polyaniline nanofiber.