The discovery of a 26 K superconductivity in the tetragonal iron-based pnictide LaFeAsO1 − xFx (x = 0.05–0.12) has stimulated a tremendous search for superconductivity in a wide class of materials with similar structure. Beside superconductivity, promising thermoelectric properties have been discovered in this family in the cryogenic temperature range and in the p-type BiCuSeO system around 400–600 °C. In this paper, we report on the effect of various substitutions on the low temperature properties of this system. Whatever the substitution, all samples revealed p-type, and no superconductivity was observed. Moreover, although some of these compounds exhibit very promising thermoelectric properties above room temperature, this is not the case in the low temperature range.