Densities and viscosities at 298.15 K are reported for the binary systems N,N-dimethylformamide (DMF) N+ N-methylformamide (NMF), NMF + water, and DMF + water and the ternary system DMF + NMF + water. The excess molar volumes and viscosity deviations of the binary and ternary systems were derived and correlated with the Redlich-Kister and Cibulka equations for the binary systems and the ternary system. The binary data were compared with the values in the literature, and the ternary data were also compared with the predicted values using the binary contribution models of Tsao-Smith, Kohler, Rastogi, and Radojkovic.