Apparent molar heat capacities C-p,C-phi and apparent molar volumes V-phi were determined for aqueous solutions of N,N-dimethylformamide and N,N-dimethylacetamide at temperatures from 278.15 to 393.15 K and at the pressure 0.35 MPa. The molalities investigated ranged from 0.015 mol . kg(-1) to 1.0 mol . kg(-1). We used a vibrating-tube densimeter (DMA 512P, Anton PAAR, Austria) to determine the densities and volumetric properties. Heat capacities were obtained using a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC 6100, Calorimetry Sciences Corporation, Spanish Fork, UT, U.S.A.). The results were fit by regression to equations that describe the surfaces (V-phi, T, m) and (C-p,C-phi, T, m). Infinite dilution partial molar volumes V(2)degrees and heat capacities C(p,2)degrees were obtained over the range of temperatures by extrapolation of these surfaces to m = 0.