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The 17O NMR spin–lattice relaxation times (T1) of solvent water molecules in aqueous solutions of amino alcohols (AA), charged amino alcohols (AA+), and charged diamines (DA2+) were determined as a function of concentration at 298 K. The values of the dynamic hydration number, nDHN = nh(τch/τc0−1), were determined from the concentration dependence of T1. The ratios (τch/τc0) of the rotational correlation times (τch) of the water molecules around each solute molecule in the aqueous solutions to that of pure water (τc0) were obtained from the nDHN and the hydration number (nh), which was calculated from the water accessible surface area (ASA) of the solute molecule. The hydrophobic hydration is disturbed by the adjacent polar groups. The effect of disturbance decreases in the following order: NH3+ > OH > NH2. The ASA dependence of the τch/τc0 value for diamines (DA), AA, and diols decreases in the following order: DA > AA > diols. When DA and AA are in a charged state, this order is reversed, namely, diols > AA+ > DA2+. The thermodynamic quantities of hydration for AA and AA+ are linearly dependent on their nDHN values.

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