The densities of l-alanine and l-serine in aqueous solutions of N,N-dimethylformamide (DMF) have been measured at 298.15 K with an Anton Paar Model 55 densimeter. Apparent molar volumes $$ (V_{\phi } ) $$ ( V ϕ ) , standard partial molar volumes $$ (V_{\phi }^{0} ) $$ ( V ϕ 0 ) , standard partial molar volumes of transfer $$ (\Updelta_{\text{tr}} V_{\phi }^{0} ) $$ ( Δ tr V ϕ 0 ) and hydration numbers have been determined for the amino acids. The $$ \Updelta_{\text{tr}} V_{\phi }^{0} $$ Δ tr V ϕ 0 values of l-serine are positive which suggest that hydrophilic–hydrophilic interactions between l-serine and DMF are predominant. The –CH3 group of l-alanine has much more influence on the volumetric properties and the $$ \Updelta_{\text{tr}} V_{\phi }^{0} $$ Δ tr V ϕ 0 have smaller negative values. The results have been interpreted in terms of the cosphere overlap model.