Densities (rho) and speeds of sound (c) of solutions of some alpha-amino acids such as glycine, l-alanine, and l-valine in aqueous ammonium dihydrogen phosphate (ADP) were measured at T = (288.15318.15) K and experimental pressure p = 0.1 MPa. By using the experimentally measured densities, the apparent molar volume (V-phi), the partial molar volume at infinite dilution (V-phi), and partial molar volumes of transfer (Delta V-phi(o)), from water to aqueous ADP have been calculated. Further, apparent molar isentropic compression (K-phi,K-s), partial molar isentropic compression at infinite dilution (k(phi,s)(o)) and partial molar isentropic compression of transfer (Delta K-phi,s(o)) were calculated from the ultrasonic speeds. The group contributions of amino acid to partial molar volumes have also been discerned. From partial molar volumes of transfer and partial molar isentropic compression of transfer, the pair and triplet interaction coefficients are attained. We have also intended partial molar expansion (partial derivative V-phi(o)/partial derivative T)(p) and second order derivative (partial derivative V-2(phi)o/partial derivative T-2)(p). The achieved results are construed in terms of (solute + solvent) and (solute + solute) interactions accompanied by structure making and structure breaking behavior of amino acids in aqueous ADP solutions.