The Chevrel phase compounds Mo6 X 8 (X = S, Se, Te) are theoretically studied by ab initio methods as potential candidates for battery cathode materials. The voltage profiles are calculated for the cases of various alkaline earth metals (Mg, Ca, Sr, Ba) serving as guest intercalation ions. The Ca ions are shown to offer the practically significant voltage of ∼1.0–1.25 V, with S substitution giving the highest voltage over Se and Te. We further demonstrate that doubling the capacity of such a battery would also be possible by incorporating a second Ca ion near the Mo6 X 8 cluster. The electronic properties of this material are investigated, revealing that the entire Mo6 cluster behaves as a redox center. Finally, the ion diffusion barriers are calculated, showing comparable values to existing battery materials. This work demonstrates that the Chevrel phase may be useful as a cathode material for intercalating divalent ions, and also offers insights into possible tuning of cathode properties by judicious selection of the constituents.