The1H-NMR spectra of liquid binary mixtures of formamide (F) and N,N-dimethylformamide (DMF), were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data were found the values of the spectral parameter, Δδ(F-DMF). The densities (d12), viscosities (η12) of the mixed solvent were measured at 298.15 K, as well as the relative permittivities (e12) at 288.15 K, 293.15 K and 303.15 K. From all these data, the molar volumes (V12) and their deviations from ideality were calculated. Additionally, the temperature coefficients of relative permittivity, α12at 298.15 K were found. These structural parameters as functions of concentration suggest the formation of stable 2F • 3DMF, F • DMF, 3F • 2DMF and 2F • DMF× type complexes.