Isothermal vapor-liquid equilibrium data are measured for seven binary systems containing ethanol and different C4 and C5 hydrocarbons : cis-but-2-ene, trans-but-2-ene, 2-methyl-but-2-ene, pent-1-ene, 2-methyl-but-1-ene, cyclopentene, and cyclopentane. The experimental synthetic method does not require the sampling of the vapor and liquid phases. The results were correlated by Peng-Robinson equation of state with the Huron-Vidal mixing rules.