Rates of sedimentation are reported for concentrated, flocculated aqueous suspensions of thorium oxide at temperatures from 150 to 325°C. Sedimentation tests were carried out in quartz tubes using a motion picture camera to follow sedimentation in the hindered settling region. The observed rates were used as a basis for calculating the effective particle diameters and densities of the sedimenting bodies at the elevated temperatures. The calculations are based on the premise that the slurries are agglomerated and that the nature of the agglomerates varies with temperature.