In this study, we investigated the electrical and thermal properties of SiC ceramics with 2 vol% equimolar Y2O3-RE2O3 (RE = Sm, Gd, Lu) additives. The three SiC ceramics with 2 vol% equimolar Y2O3-RE2O3 additives showed electrical conductivities on the order of similar to 10(3) (m)(-1), which is one order of magnitude higher than that of the SiC ceramics sintered with 2 vol% Y2O3 only. The increase in electrical conductivity is attributed to the growth of heavily nitrogen-doped SiC grains during sintering and the confinement of oxide additives in the junction area. The thermal conductivities of the SiC ceramics were in the 176-198 W(mK)(-1) range at room temperature. The new additive systems, equimolar Y2O3-RE2O3, are beneficial for achieving both high electrical conductivity and high thermal conductivity in SiC ceramics.