[en] Adsorption of cobalt on haematite and zirconia has been studied in the temperature range 298 to 328K, with room temperature pH values between 6.6 and 8.0. The ionic strength was kept constant for most of the experiments at 0.1M, using sodium nitrate, although the effect of altering it was investigated briefly. The extent of cobalt adsorption on haematite and zirconia was found to increase with temperature, with pH, and with decreasing ionic strength. As the PWR primary coolant pH is raised, it is likely that cobalt uptake on zirconia films will increase, but the extent of the adsorption cannot be predicted from the present study. A series of autoclave experiments is therefore planned to study cobalt uptake as a function of water chemistry at temperatures representative of the PWR primary coolant. (author)