The enthalpies of solution of urea and its N-methyl-substituted analogues (methylurea, 1,1-dimethylurea, 1,3-dimethylurea, and 1,1,3,3-tetramethylurea) in water and methanol were measured at 298.15 K. Enthalpies of transfer from water to methanol were calculated. The enthalpies of transfer of methyl-substituted ureas are endothermic, the enthalpy of transfer of urea is negative. It has been concluded that the structure-making effects do not play the key role in methanol. The earlier assumption of an independent solvation of either side (alkylated or unsubstituted amino group) of the molecules is supported. (c) 2006 Elsevier B.V. All rights reserved.