Poly(γ-glutamic acid) (γ-PGA) and its partially benzylamidated (hydrophobized) derivatives were prepared and studied in solution by means of dynamic light scattering (DLS), 1D, 2D and PGSE NMR in order to determine the structure, size and aggregation in solution. By pH potentiometric titrations in aqueous solution the apparent pK ≈ 4 of γ-PGA was determined. The measured diffusion coefficients as a function of pH showed the swelling of γ-PGA by deprotonation of carboxyls. DLS measurements showed a certain degree of aggregation even in dilute solution. The degree of aggregation is increased in the presence H2PO4- and HPO 42- buffer anions. Benzylamidation of 30-50% of caboxylates resulted in folded structure of the BzPGA, probably spherical like nanoparticles, verified by NMR diffusiometry and 2D NOE spectroscopy.