The adsorption of simulated fission products on slurries of ThO2-UO3 mixtures has been studied. Experiments were performed using tracer techniques employing slurries which had been previously pumped in order that the condition of the slurry as well as concentration of the fission products, temperature, and pressure might simulate reactor conditions. Results of some preliminary experiments designed to remove fission products by the use of eluting agents are also reported.