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The adsorption of cobalt on lead dioxide from aqueous solutions has been optimized with respect to the shaking time, the amount of adsorbent, the pH and the concentration of adsorbate at 293 K. Under such optimum conditions, the adsorption of cobalt on lead dioxide has been studied at different temperatures and the process found to be endothermic with the distribution coefficient (K D ) increasing with increasing temperature. The data fitted very well to the Langmuir, Freundlich and Dubinin–adushkevich isotherms, allowing the corresponding constants to be calculated. Values of ΔH 0 and ΔS 0 were calculated from the slope and intercept of the plots of In K D versus 1/T. The value of ΔG 0 , which decreased with increasing temperature, showed that the adsorption is more favourable at higher temperatures.