Organic thin films are of increasing importance as electronic material for various applications like, for example, organic light emitting diodes (OLEDs) and dielectric thin films in organic field effect transistors (OFETs). The surface morphology and the local electric conductivity of these films are of particular importance for their functionality. In this thesis, the surface morphology and electrical conductivity of dielectric parylene layers as well as photoreactive polyaniline thin films were investigated. For this purpose, conductive atomic-force microscopy (C-AFM) was applied. C-AFM allows a simultaneous determination of the surface morphology and the electrical conductivity on the nanometer-scale. Parylene films on Ag/glass showed good insulating behavior, but poor mechanical resistance. The surface of parylene on Ag/glass is uneven with an RMS roughness of 3.5 nm. The voltage dependence of the tunneling current through the films, could not be explained by Fowler-Nordheim behavior. The polyaniline thin films were illuminated by UV-light through masks which were patterned in the micrometer range. The conductivity of the photosensitive polyaniline thin films increased upon ultraviolet (UV) light exposure to a value just above the detection level of the used C-AFM. A significant increase in conductivity of the UV illuminated areas could be achieved via protonation in HCl vapor.