Order-order and/or order-disorder transitions associated with changes of intercalate interlayer stacking sequences in stage-1 alkali graphite intercalation compounds are studied within a framework of mean-field lattice gas model. The species dependence of the interlayer stacking phases and phase transitions in binary compounds MC8 (Mp=K, Rb, Cs) as well as in ternary compound KCsC16 is described in terms of the present lattice gas model.
