The electrical, thermal, and mechanical properties of three different porous SiC ceramics with boron-containing additives were investigated as functions of additive content, sintering atmosphere, and sintering temperature. The results suggest that (1) the thermal conductivity and flexural strength of porous SiC ceramics can be tuned independently from the porosity by controlling carbon content and sintering temperature; (2) the electrical resistivity of the porous SiC ceramics was primarily controlled by the sintering atmosphere owing to the N-doping from the nitrogen atmosphere, and secondarily by the B-containing additive (B4C, BN) content, owing to the B-doping from the B-containing additives; (3) the thermal conductivity and flexural strength were dependent on both the porosity, and necking area, as influenced by both the sintering atmosphere and B-containing additive content; and (4) it was possible to decouple the electrical resistivity from the thermal conductivity by judicious selection of the B-containing additive content and sintering atmosphere. Typical electrical resistivity, thermal conductivity, and flexural strength of porous SiC ceramics with 1 wt% B4C-4 wt% C sintered at 2100 °C were 1.3 ´ 10-1 Ω·cm, 76.0 W/(m·K), and 110.3 MPa, respectively.