Investigations of recently cracked concretions from the Carboniferous Montceau-les-Mines, France, Lagerstätte led to the recognition of two new malacostracan Crustacea: a palaeophreatoicid isopod, Sottyella montcellensis n. g., n. sp., and a gorgonophontid stomatopod, Chabardella spinosa n. g., n. sp. The occurrence of the palaeophreatoicid isopod Palaeocrangon is discussed, and a new specimen of the syncarid Palaeocaris secretanae allows us to clarify some of its morphological characters. The recognition of these taxa increases the faunal inventory of malacostracans in the Montceau-les-Mines Lagerstätte.