Hexagonal boron nitride (h-BN) ceramic was successfully fabricated by pressureless sintering at 2100uC using submicrometre h-BN powders without any sintering additive. The as prepared h-BN ceramic showed a room temperature flexural strength of 30?7 MPa. Its flexural strength increased with the increment of temperature in N 2 atmosphere, and it retained a strength of 57?2 MPa (nearly two times of the room temperature strength) at 1600uC due to clean grain boundaries with no glassy phase. Additionally, the as prepared h-BN ceramic showed a high thermal conductivity of 31?76 W m 21 k 21 and a good thermal shock resistance, which retained a relatively high residual flexural strength of 22?6 MPa (73?5% of the original flexural strength) at DT5800uC. The as prepared h-BN ceramic presents a good application prospect at high temperature.