Additions of 0. 5 to 2. 0 mol% of CoO or MnO2 onto SnO2 promote densification of this oxide up to 99% of theoretical density. The temperature of the maximum shrinkage rate (TM) and the relative density in the maximum densification rate (p*) during constant sintering heating rate depend on the dopant concentration. Thus, dopant concentration controls the densifying and nondensifying mechanisms during sintering. The densification of SnO2 witih addition of CoO or MnO2 is explained in terms of the creation of oxygen vacancies.