CaMoO4 nanocakes with uniform size and morphology were prepared on a large scale via a room temperature reverse-microemulsion method. The products were characterized in detail by X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. By establishing the relations between the thermodynamic functions of nano-CaMoO4 and bulk-CaMoO4 reaction systems, the equations for calculating the surface thermodynamic functions of nano-CaMoO4 were derived. Then, combined with in-situ microcalorimetry, the molar surface enthalpy, molar surface Gibbs free energy, and molar surface entropy of the prepared CaMoO4 nanocakes at 298.15 K were successfully obtained as (19.674 ± 0.017) kJ·mol−1, (619.704 ± 0.016) J·mol−1, and (63.908 ± 0.057) J·mol−1·K−1, respectively.