Samarium hexaboride (SmB6) powders were synthesized by boro/carbothermal reduction of Sm2O3 with B4C. Nominally pure SmB6 powder had a mean particle size of about 400 nm and an oxygen content of 0.12 wt%. SmBO3 formed as an intermediate phase during the synthesis. The synthesized powder was hot pressed at 1950 degrees C to produce SmB6 ceramics with relative densities >99.6% and a mean grain size of 4.4 m. Vickers' hardness was 20.1 +/- 0.7 GPa. Young's modulus measured by bending and ultrasonic methods was 271 and 244 GPa, respectively. The flexure strength was 253 +/- 79 MPa and fracture toughness was 2.1 +/- 0.1 MPa m(1/2). These are the first reported results of the microstructure and bulk mechanical behavior of SmB6 ceramics.