As the demand for energy is increasing world wide, not only the security of energy supply and the stability of prices, but also climate change has become an important issue. The production of synthetic natural gas from biomass could be one route to address these issues. The advantages are the high conversion efficiency, the existing gas pipelines, the efficient end-use technologies and the recovery of a concentrated CO2 stream ready for carbon capture and storage. Within the EU project Bio-SNG a process development unit was erected that demonstrated the complete process chain from wood to SNG in half-commercial scale. The heart of the unit is a 1 MW fluidized bed methanation reactor. This thesis aims to increase the understanding of the different processes within such a reactor. A deeper inside was gained by dedicated experiments using spatially resolved measurement techniques. In addition, a fluidized bed model was developed using hydrodynamic parameters from the literature and kinetic parameters determined within this work. Modeling of a bench-scale unit showed that the initial slope of the gas composition profiles and the outlet composition could be reproduced.