AuCl 3 -GIC has a significantly short c-axis lattice constant due to the planar molecule Au 2 Cl 6 intercalate which are tilted by 15° with respect to the graphitic layers. We report the specific heat, c-axis compressibility and thermal expansion of stage-1 AuCl 3 -GIC to clarify the lattice dynamics related to the AuCl 3 intercalates. Lattice specific heat deviates from ordinary T 3 dependence where the Debye temperature varies from 120-160 K, suggesting the presence of low energy phonons of heavy AuCl 3 intercalates as well as the acoustic phonons. Thus, the c-axis compressibility and the thermal expansion are analyzed in terms of one-dimensional Debye contribution of the longitudinal acoustic phonon and the libron modes associated with the rotation of the AuCl 3 intercalate. θ D is estimated to be 440 K, while the libron contribution, which plays a major role at low temperatures below 50 K, is explained with the Einstein temperature θ E = 33 K. The Guneisen parameters are estimated to be Γ D = 2.49 and Γ E = 0.46, concluding that the c-axis lattice expansion comes mainly from the c-axis longitudinal acoustic phonon, in spite of its lattice stiffness being much stronger than that expected for the libron mode.