The structural properties of Mn0.92Fe0.08CoGe have been investigated in detail using synchrotron x-ray diffraction in zero and applied pressure (p = 0–10 GPa). A ferromagnetic transition occurs around TC = 300 K and a large magnetic-entropy change −ΔSM = 17.3 J/kg K detected at TC for a field change of ΔB = 5 T. The field dependence of −ΔS M max can be expressed as −ΔS M max ∝ B. At ambient temperature and pressure, Mn0.92Fe0.08CoGe exhibits a co-existence of the orthorhombic TiNiSi-type structure (space group Pnma) and hexagonal Ni 2In-type structure (space group P63/mmc). Application of external pressure drives a structure change from the orthorhombic TiNiSi-type structure to the hexagonal Ni 2In-type structure. A large anomaly in heat capacity around TC is detected and the Debye temperature θD (=319(±10) K) has been derived from analyses of the low temperature heat capacity, T ≲ 10 K.