The standard molar enthalpy of formation of crystalline di-n-propyldithiocarbamate complexes of P, As, Sb and Bi(III) was determined through reaction-solution calorimetry in acetone, at 298.15 K, giving -661.10+/-5.04, -305.07+/-5.50, -366.62+/-1.70 and -358.98+/-1.70 kJ mol(-1), respectively. The corresponding standard molar enthalpies of sublimation were 127.36+/-4.24, 145.07+/-5.30, 169.45+/-6.08 and 185.24+/-5.03 kJ mol(-1), respectively, estimated by means of differential scanning calorimetry. By combining the preceding values with the standard molar enthalpies of formation of the chelates in the solid phase, the standard molar enthalpies of formation in the gas phase was obtained as -533.74+/-7.28, -160.00+/-6.10, 197.17+/-6.31 and 173.74+/-5.31 kJ mol(-1), respectively. From the standard molar enthalpies of formation of the gaseous chelates, the homolytic values were 217.3+/-3.1, 153.0+/-3.0, 152.5+/-3.0 and 139.5+/-2.9, and the heterolytic values were 1091.3+/-3.1, 969.2+/-3.0, 867.1+/-3.0 and 838.5+/-2.9 kJ mol(-1), and the mean metal-sulphur bond-dissociation enthalpies were calculated.