Thermodynamic and kinetic characteristics of the Sc-D system are investigated as a complement to the earlier studies of the Sc-H system. A Sieverts apparatus is employed to conduct the measurements. The Sc-D system is characterized by two phase regions: the metal-rich and the deuteride phases. The equilibrium plateau relationships in the two-phase regions are determined from the Van’t Hoff plots and found to be: $$ \ln P({\text{Pa)}} = {{\left( {-{\text{ 16374}}{\text{.48}} \pm{\text{188}}{\text{.88}}} \right)} \mathord{\left/ {\vphantom{{\left( {{\text{ - 16374}}{\text{.48}} \pm{\text{188}}{\text{.88}}} \right)} T}} \right.\kern-\nulldelimiterspace} T} + ({\text{23}}{\text{.56}} \pm{\text{0}}{\text{.18)}}$$ . The enthalpy and entropy of reaction are calculated to be (−136.14 ± 1.57) kJ mol−1 D2 and (−100.06 ± 1.50) J mol−1 K−1 D2, respectively. From the relationship of ln[(P0−Pf)/(P−Pf)] and time t, the reaction of the Sc-D system is confirmed to be a first-order reaction in the temperature range of 923–1,073 K. The temperature has a negative effect on the reaction rate (ka), which decreases from 0.0717 to 0.0130 s−1 with the temperature increasing from 923 to 1,073 K. In addition, a minus activation energy of (−93.87 ± 6.22) kJ.mol−1 is acquired. However, once increasing temperature up to 1,123 K, the relationship of ln[(P0−Pf)/(P−Pf)] and time t firstly satisfies an exponential equation of y = −0.5471exp(−x/9.1879) + 0.00272. After 50 s, it begins fitting a linear equation again, indicating the various reaction mechanisms.