The heat capacity of thallium(I) n-decanoate was measured by adiabatic calorimetry from 6 to 350 K and by d.s.c. from 200 through 480 K. Excellent overlap occurs over the common temperature range of both techniques. Four solid-to-solid transitions were found; at 232.9 K, at 288.3 K, and two more at 305.6 K (very sharp with a for the maximum of about 1700R), and at 327.6 K. The corresponding values of ΔtrsHmo are 352R·K, 83.8R·K, and 1026R·K (for the set of two transitions), respectively, and of ΔtrsSmo are 1.461R, 0.283R, and 3.19R (for the set of two), respectively. The compound melts to a liquid-crystal phase at 450.0 K: ΔtrsHmo = 682R·K, ΔtrsSmo = 1.68R. Finally, "clearing" occurs at 484.0 K: ΔtrsHmo = 307R·K, ΔtrsSmo = 0.63 R. Smoothed thermophysical functions are tabulated through "clearing" at selected temperatures.Partial support of this research by the CAICYT of the Spanish Ministerio de Educatión y Ciencia (Grant in aid for Scientifk Research PB85-0042) is gratefully acknowledged.Peer reviewed