The enthalpy, entropy and free energy changes have been determined for the transfer, at 25°C and 1 atm, of cyclic amines of the type CnHznNH (n = 4,5,6) and CnHZnNCH3 (n = 4,5), from either the ideal gas state (AXh, X = H,S,G) or the liquid state (AX,, X = H,S,G) to dilute aqueous solution. Heats of solution of compounds of the type CnHZnNH with n = 2,3,7 and heats of vaporization (AHv) for all the above compounds are also reported.In the CnHznNH series the heat of solution, which is exothermic, has a maximum at n = 4, whereas AH, values increase in the homologous series from 8.09 kcal mol-1 (n = 2) to 11.04 kcal mol-l (n = 7). The heats of solution of the N-methyl amines are larger than those evolved on solution of the corresponding secondary, unsubstituted amines, while the AH, values are practically equal. On the other hand, a sensible decrease of Ash is caused by introducing a methyl group on the nitrogen atom. Possible interpretations of the observed effects are suggested.