Two asymmetrical Se-containing donor molecules ESET-TTF and CHET-STF were synthesized and their cation radical salts were investigated. κ-(ESET-TTF) 2 CuN(CN) 2 Br is semiconductive at ambient pressure and shows an abrupt drop of resistivity under pressure (4.7 K, 3.2 kbar) which suggests a superconducting transition. (CHET-STF) 2 PF 6 has almost the same structure with the corresponding TMET-STF salt. This salt is metallic down to 1.6 K, while (TMET-STF) 2 PF 6 is semiconductive in all the temperature region.