The wet grinding temperatures of two kinds of fine ceramics ; normally sintered silicon carbide (SSC) and normally sintered silicon nitride (SSN); are measured by means of an infrared radiation pyrometry, in which a PbS-cell is mounted just below the workpiece. This new direct-type pyrometer makes it possible to measure the temperature above approximately 50°C. The grinding zone temperature is affected by the abrasive-workpiece interaction. The maximum grinding zone temperature below 100°C is obtained with soluble-type grinding fluid for SSC, in which the finished surface is highly fragmented with less flow. In the case of SSN, more flow and less fragmentation of the finished surface is observed, which causes higher grinding zone temperature. Influence of grinding conditions on the grinding temperature of SSN is greater than that of SSC, especially the grinding zone temperature rises considerably as workpiece velocity increases in wet grinding.