The experimental data of P, T, x, y isothermal vapour-liquid equilibri
um at 333.15, 343.15 and 363.15 K in cyclooctane-toluene mixture are p
resented. Use has been made of an ebulliometer which allowed sampling
from both phases in equilibrium. The experimental data were processed
for evaluation of thermodynamic consistency. The results have evidence
d a slightly positive deviation from ideality of the system.