The article presents the results of experimental research on the grinding of corundum ceramics in the pre-sintered state, with spherical diamond heads. The aim of the experiment was to determine the effect of grain size and feed rate on selected aspects of the grinding process of corundum ceramics with the use of spherical diamond heads. In the experiment, grinding wheels with a ball diameter of 3 mm and different grain sizes were used; the grain numbers were D64, D91, D126 and D181. The tests were carried out on the Ultrasonic 20 Linear machining center at a constant rotational rate of the grinding wheel n = 38,000 rpm and a grinding depth of 30 µm. The feed rate was set on 3 values: 200, 400 and 600 mm / min. During the research, the process temperature was recorded with a thermal imaging camera. The topography of grinding wheels before and after the grinding process and the topography of the ground surface were also measured. The parameters Sa and Ŝz (Ŝz= Spk+Sk+Svk) were used to characterize the grinding heads. The conducted analyses showed the dependence of the parameters Sa and Ŝz of new grinding heads on the grain size described by the quadratic function (R^(2 )≥0.94). Statistically significant changes in the parameters Sa and Ŝz on the cutting surface of the grinding wheel, which occurred as a result of its wear, were observed. There was no significant relationship between the feed rate and the wear of grinding heads, probably due to the relatively small volume of the material removed. A positive correlation between the Sa and Ŝz parameters of the ground object and the grain size was observed. The research also showed an increase in the process temperature with an increase in the feed rate and an increase in the grain size.