Densities (rho) and viscosities (eta) of aqueous 1-methylpiperazine (1-MPZ) solutions are reported at T = (298.15 to 343.15) K. Refractive indices (n(D)) are reported at T = (293.15 to 333.15) K, and surface tensions (gamma) are reported at T= (298.15 to 333.15) K. Derived excess properties, except excess viscosities (Delta eta), are found to be negative over the entire composition range. The addition of 1-MPZ reduces drastically the surface tension of water. The temperature dependence of surface tensions is explained in terms of surface entropy (S(s)) and enthalpy (H(s)). The measured and derived properties are used to probe the microscopic liquid structure of the bulk and surface of the aqueous amine solutions. (C) 2011 Elsevier Ltd. All rights reserved.