Density and sound velocity of the solutions of ionic liquids based on N-alkyl-N-methyl-morpholinium cations: N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-octyl-N-methyl -morpholinium bis(trifluor omethanesulfonyl)imide and N-decyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide in N,N-dimethylformamide and N,N-dimethylacetamide were measured at T = (298.15-318.15) K and at atmospheric pressure. Using experimental data, apparent molar volume and apparent molar compressibility values were calculated and fitted to the Redlich-Meyer type equation which was used to obtain partial molar volume and partial molar isentropic compressibility of the ILs at infinite dilution. By using the density data, the isobaric thermal expansibility coefficients were also estimated. The effect of alkyl chain length of the ILs, experimental temperature and properties of solvent on these thermodynamic properties were discussed. (C) 2018 Elsevier Ltd.