With a static type equilibrium cell and the pressure decaying method, the solubility of ethylene in a mixture of 2,2,4-trimethylpentane and 1 octene was measured in the temperature range of 323.15-423.15 K, pressure range of 5-25 bar, and 1-octene concentration from 0 to 85 wt%. The experimental results show that the solubility of ethylene in a 2,2,4-trimethylpentane and 1-octane mixture increases with system pressure but decreases with system temperature. The experimental solubility data were also expressed in the vapor-liquid equilibrium relationship and correlated by the bubble pressure calculation using the Peng-Robinson equation of state (PR EOS) incorporated with the van der Waals one-fluid and the Zhong-Masuoka mixing rules. Among the deviations between the experimental and correlated results, the largest value of average absolute relative deviation is 1.73% for pressure at 423.15 K and that of average absolute deviation is 0.0024 mol fraction for vapor composition at 373.15 K by the Zhong-Masuoka mixing rule. (C) 2007 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.