Densities of highly dilute solutions of protiated and deuterated water in N,N-dimethylformamide and N,N-dimethylacetamide, with the solute mole fractions ranging up to 0.012, were measured with an error of 1.0.10(-5).cm(3).mol(-1) at T = (278.15, 288.15, 298.15, 308.15 and 318.15) K and atmospheric pressure using a precise sealed vibrating-tube densimeter. Apparent molar volumes and apparent molar isobaric expansibilities (down to the infinite dilution) of water isotopologues were calculated. The temperature-dependent behavior of D2O-H2O solute isotope effects on the apparent molar quantities under study were described taking into account the structural features of the amide-solvating media compared. (C) 2012 Elsevier Ltd. All rights reserved.