Isobaric vapor-liquid equilibria of binary systems formed by formic acid + N,N-dimethylformamide or + 2-ethyl-1-hexanol as well as N,N-dimethylformamide + 1-chloro-2-ethylhexane were estimated at a pressure of 10.00 kPa. Mutual solubilities of formic acid + 1-chloro-2-ethylhexane were determined within the temperature range of (20 to 80) degrees C. The binary equilibrium data were fitted to the Redlich-Kister, Wilson, and NRTL equations employing the maximum likelihood procedure. Binary parameters of the chosen excess molar Gibbs energy models were calculated assuming ideal behavior of the vapor phase. A comparison of the goodness of fit of the selected G E models is presented.