The authors have measured the vapour pressure of the binary systems, piperidine+n -butylamine, piperidine+dipropylamine, piperidine+N-methyl piperidine, piperidine+N,N-dimethyl amino butane and N-methyl
piperidine+n -butylamine. The measurements were carried out using an isoteniscope built by Jose . The vapour pressure, excess Gibbs
free energies at 298,15, 303,15, 313,15, 323,15, 333,15, and 325,15 K, are reported for these mixtures. The excess Gibbs free
energies have been fitted to Redlich-Kister equation.