This paper presents the results of comparative experimental tests of proper active powers and maximum temperatures, conducted on the circumference grinding of flat surfaces, made of grade 321 corrosion-resistant steel (1.4541), using modern aluminium oxynitride and noble electrocorundum vitrified-bonded grinding wheels. The tests were carried out in both up-cut and down-cut conditions. In both kinematic grinding aspects, the tested factors were determined by discrete increase of reductive grinding yield, applying increasing grinding-wheel in-feed to the workpiece and keeping the remaining grinding parameters at the constant level. The test results were later subjected to simplified statistical analysis, and an attempt was made at substantive test justification. It was demonstrated that, regardless of the assumed kinematic grinding aspects of steel grade 1.4541 (321), the values of all the comparatively tested values of aluminium oxynitride grinding wheels were, with increasing reductive grinding yield, lower than the corresponding values of the noble electrocorundum grinding wheels.