[en] This thesis reports on plasma-surface interactions in fusion machines like the tokamak and the reversed field pinch device. The studies have been performed using surface probes exposed to plasma from the TEXTOR tokamak and the EXTRAP T1 device. In the simulation experiments probes have been exposed to plasma in a laboratory glow discharge chamber and irradiated with ion beams from accelerators. Some samples were irradiated with neutrons from a fission reactor. Different types of graphite, silicon, stainless steel, amorphous hydrogenated and boron doped carbon films have been investigated. The alterations of the surface elemental composition, layer thickness or profiles of components are discussed and related to plasma-wall interaction processes like impurity production by sputtering or arcing, surface erosion, redeposition of hydrogen and carbon, or hydrogen isotope exchange processes. Studies of boron fluxes in the SOL of TEXTOR, collected on surface probes in different experiments throughout one year following boronization, allowed us to understand the erosion processes of boron in the machines with high and very low concentration of boron, attributed to physical and chemical erosion respectively. The influence of radiation damage due to helium ions and fission neutrons on hydrogen trapping or release from different materials has been studied. Experiments on deuterium retention in the graphite surfaces, depending on the exposure time, allowed the determination of the particle fluxes to the wall at EXTRAP T1, the mean energy of impinging plasma ions and neutrals and estimation of the particle confinement time. Part of the work is concerned with neutron radiation measurements around high energy electron accelerators. The surface analyses of exposed samples have been performed by a post-mortem analysis, mainly using ion beam techniques. (139 refs.)