Electrical transport calculations show that the power factors of Bi 2 SO 2 and Bi 2 SeO 2 are limited by the degredation of the Seebeck coefficient due to the heavy doping required to obtain a reasonable electrical conductivity, whereas the low intrinsic |S| of Bi 2 TeO 2 is offset by a larger σ. On the other hand, the alternative p-type doping is predicted to yield a smaller σ but considerably larger S for Bi 2 SO 2 and Bi 2 SeO 2 , potentially resulting in larger PFs at high n, A detailed microscopic analysis of the lattice (phonon) thermal conductivity suggests the stronger chemical bonding and lighter O atoms in the oxychalcogenides lead to larger group velocities but stronger anharmonic phonon-phonon interactions than in the bismuth chalcogenides Bi 2 Ch 3 and SnS/SnSe.