Polymeric beads are valuable tools for a variety of applications in chemistry, e.g. separation and synthesis support. A common property of all applications is, that diffusion processes and mass transport balances play an important part and are heavily dependent upon matrix parameters such as crosslinking. We have applied 1H and 19F-microscopy to monitor diffusion processes in differently crosslinked polystyrene beads (CL-PS). MRI is used primarily as a medical diagnostic method, but has begun to find increasing application in material science, including studies of fluids in polymers [1,2].