Densities of binary liquid mixtures of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [bmpyr][NTf2], with N-methylformamide (NMF) and N,N-dimethylformamide (DMF) were measured at temperatures from (293.15 to 323.15) K and at atmospheric pressure over the whole composition range. Excess molar volumes, V-E, have been obtained from the experimental densities and were fitted to Redlich-Kister polynomial equation. Other volumetric properties, such as isobaric thermal expansion coefficients, partial molar volumes, apparent molar volumes and partial molar volumes at infinite dilution have been also calculated, in order to asses the formation of hydrogen bonds in NMF or their absence in DMF on the interactions with selected ionic liquid.