Low-temperature specific heat measurements were performed on a series of binary, pseudobinary, ternary and pseudoternary molybdenum chalcogenides MxMo6X8. The measurements covered a sufficiently wide temperature range to yield the relevant moments of the phonon spectra in addition to the electronic term. From the data in the superconducting state, strong coupling parameters were also obtained, particularly the gap ratios 2∆(0)/kTC°. The superconducting transition temperature of the Chevrel-type phases essentially depends on the bare electronic density of states at the Fermilevel and, moreover, on the atomic order pertaining to the Mo6 and certain chalcogen sites. For the ordered compounds, the relation λ ≈aNbs(EF) holds on the average. The factor a≈1.25 eV Mo atom spin is practically equal to that found for Nb-based A15-type cmpounds.