Our calculations predict that Pnma GeS and GeSe can achieve larger ZT max with n-type doping compared to the p-type doping typically targeted in experiments. The averaged ZT max of 2.12 for Pnma GeSe is comparable to our predicted 2.07 for p-type Pnma SnSe and suggests n-type GeSe may make a good partner for SnSe in a thermoelectric couple. n-type doping results in the the maximum electrical conductivity and minimum κ latt being aligned along the layered b direction, and we predict a much larger ZT max > 3 for Pnma GeSe if the growth direction can be controlled. The same appears to be true for n-type SnSe, where the average ZT max with n-doping is predicted to be 15% larger than with p-type doping and the directional ZT along the b axis is predicted to be 4.32. Our results therefore suggest that fur-Table Predicted maximum thermoelectric figure of merit, ZT max , of the R3m and Pnma phases of GeS and GeSe for temperatures up to the phase transitions in the orthorhombic phases. Separate values are provided for both p-and n-type doping together with the corresponding temperature, carrier concentration n and properties in Equation 1, viz. the electrical conductivity σ , Seebeck coefficient S, power factor (PF) S 2 σ , electronic and lattice contributions to the thermal conductivity κ el /κ latt , and total thermal conductivity κ tot . We also show data for Pnma SnS and SnSe from our previous study for comparison. ther exploration of the Ge chalcogenides, and of the possibility of n-type doping of both the Sn and Ge chalcogenides, will be a fruitful direction for future research.