Alkanolammonium ionic liquids such as (2-hydroxyethyl)ammonium hexanoate ([2HEA][Hex]), bis(2-hydroxyethyl)ammonium hexanoate ([BHEA][Hex]), and tris(2-hydroxyethyl)ammonium hexanoate ([THEA] [Hex]) were synthesized and characterized by ¹H NMR and FTIR, respectively. The thermophysical properties such as density, viscosity, and thermal stability of all alkanolammonium ionic liquids were measured at several temperatures and 0.1 MPa. The excess molar volumes for binary mixtures of alkanolammonium ionic liquids + water at temperatures between 298.15 K and 343.15 K were also determined over the entire composition range. The excess molar volumes were correlated with the Redlich-Kister equation with average absolute deviations smaller than 0.0164. The viscosities of pure alkanolammonium ionic liquids were regressed using two models: the Ostwald-de Waele relationship and the Vogel-Fulcher-Tammann equation. The influence of the degradation mechanism on thermal stability was examined by thermogravimetry. The results showed a degradation stage above 100 ◦C for all alkanolammonium ionic liquids. The impact of cation and anion carbon numbers on the thermophysical properties of alkanolammonium ionic liquids is discussed.