A wide family of cobalt oxides of formulation (Pr 1−y Ln y ) 1−x Ca x CoO 3 (Ln being a lanthanide) exhibits a coupled valence and spin-state transition (VSST) at a temperature T*, which involves two concomitant modifications: (i) a change in the spin state of Co 3+ from low-spin (T < T*) to a higher spin-state (T > T*), and (ii) a change in the valence state of Pr, from a mixed Pr 4+ /Pr 3+ state (T < T*) to a purely trivalent state (T > T*), accompanied by an equivalent charge transfer within the Co 3+ /Co 4+ subsystem. In the present paper, the VSST taking place in (Pr 0.7 Sm 0.3 ) 0.7 Ca 0.3 CoO 3 at T* 90 K is investigated by magnetization and heat capacity measurements. First , we quantitatively characterized the jumps in magnetic susceptibility () and entropy (S) around T*. Then, these values were compared to those calculated as a function of the variations in the population of the different cationic species involved in the VSST. X-ray absorption spectroscopy experiments recently showed that the higher spin state above T* should be regarded as an inhomogeneous mixture between lowspin (LS) and high-spin (HS) states. In the frame of this description, we demonstrate that the jumps in both and S can be associated to the same change in the Co 3+ HS content around T*. This result lends further support to the relevance of the LS/HS picture for the VSST, challenging the currently dominant interpretation based on the occurrence of an intermediatespin (IS) state of Co 3+ above T*.