The heat capacity of CrSbz has been measured by adiabatic calorimetry from 5 to 991.3 K. At the latter temperature the CrSb,-phase decomposes into the CrSb-phase and an antimonyrich melt. The heat capacity of the two-phase mixture was measured from 991.3 to 1050 K. The heat capacity of CrSb, shows a small sharp h-type transition with a maximum at 274.1 K where the change from the antiferromagnetic to the paramagnetic state occurs. Thelow entropy of the clearly cooperative part of the transition, A& = 0.12 calth K-l mol-I, shows that this contribution is only a small part of the total. From an estimate of the lattice heat capacity of CrSbz outside the h-transition region we find an excess heat capacity amounting to about 1.7 calth K-l mol-l at 300 K, 1.6 calth K-l mol-' at 500 K, and 1.1 calth K-' mol-1 at 800 K, which we attribute to the population of excited electronic states in CrSbz. The total transitional entropy amounts to about 2.6 cal,,, K-l mol-1 at 900 K only slightly more than the R In 3 (= 2.17 calth K-l mol-') expected from randomization of two unpaired spins per chromium atom. The enthalpy of the peritectic decomposition of CrSb, at 991.3 K is (8325120) calth mol-I. The high heat capacity above 991 K is presumably related to the solution of CrSb(s) in the meh. Thermodynamic functions have been evaluated and the values of C,, {S"(T)-s"(O)}, and-{G"(T)-H'(O)]/T at 298.15 K are (19.66*0.02), (27.46*0.03), (14.OO9&0.014) calth K-l mol-I. CrSb, loses antimony on approaching the peritectic temperature and the composition of the decomposing phase is in the range CrSb,,,, to CrSbl.g5. To explore further the homogeneity range of the CrSba-phase some heat-capacity measurements on CrSb1.85 have also been carried out. Combination of the present results with standard Gibbs energies of formation at 850 K from the literature gives for CrSbz.ao: 298.