Isobaric vapor-liquid equilibria (VLE) were measured for the ternary system dibutyl ether + 1-pentanol + nonane and for two constituent binaries systems, dibutyl ether + nonane and dibutyl ether + 1-pentanol, at the pressures (26.66, 53.33, 79.99, and 101.32) kPa. Boiling temperature (T, x) relations were obtained by using a semi-microebulliometer. 1-Pentanol formed a minimum boiling azeotrope with dibutyl ether. The modified Wilson model with parameters that linearly depend on temperature was used to correlate to the binary T, x data and to predict VLE in the ternary system.