Abstract: The Ni montmorillonite catalyst is prepared from raw bentonite and its activity of catalytic oxidation is evaluated in the desulfuration from liquid phase. The deter-mined and analysed results of DTA and TPR show that the exchangeable Ni-ions between the sheets of the montmorillonite can immediately combine with oxygen to form oxides under higher temperature. The effect of the oxidation on the drop of the catalytic activity of Ni montmorillonite is probably more important than that of the Ni-ions embed in the sheet structure due to heat-activation.