The heat capacity of cadmium oxysulfate (2cdo . Cdso4) from 5.16 To 300.7 K was measured by adiabatic calorimetry and the relative enthalpy to 1001.5 K by copper-block drop calorimetry. A nonisothermal transition was observed over the temperature range 245 to 260 k with a peak at 253 k. The values at 298.15 K for c deg p,m, s deg m(t) - s deg m(o) , - g deg m(t) - h deg m(o) /t, and h deg m(t) - h deg m(o) are 193.67, 246.59, and 125.81 J . K-1 . Mol-1, and 36.01 Kj . Mol-1, respectively. These properties are also reported at convenient temperature intervals from 5 to 1000 k.