The binary vapour-liquid equilibrium of seven systems of epsilon-caprolactam + octane, + decane, + dodecane, of N-methylacetamide + octane, of N-ethylacetamide + decane, of N-methylpropionamide + octane and of N-methylpropionamid + epsilon-caprolactam was measured in the temperature range from 363 to 423 K and in the low pressure region. A static equilibrium apparatus for the measurements was constructed. In the system N-methylpropionamide + octane measurements of liquid-liquid equilibrium were carried out in the temperature range from 310 K up to the critical solution temperature. The experimental results were correlated applying activity coefficients models such as NRTL. The data obtained from our measurements were used to estimate UNIFAC interaction parameters for the groups CH2/CONHCH2, CH2/C5H10CONH and CONHCH2/C5H10CONH.