Accurate knowledge of the phase equilibria of CO(2)-expanded hydroformylation reaction mixtures is essential to rational process design and development. Vapor-liquid equilibria of the following systems were measured in a variable-volume view cell at temperatures ranging from (313.15 to 353.15) K and pressures up to 9 MPa: CO + 1-octene, CO(2) + 1-octene, CO + 1-octene + CO(2), CO + nonanal, CO(2) + nonanal, CO + nonanal + CO(2), H(2) + 1-octene, H(2) + 1-octene + CO(2), H(2) + nonanal, and H(2) + nonanal + CO(2). The measured solubilities of CO and H(2) in the liquid phases were consistent with literature values. The presence of CO(2) was found to enhance the solubilities of both CO and H(2) in the liquid phase. The enhancement factor is up to 1.54 for carbon monoxide and 1.82 for hydrogen. The Peng-Robinson equation of state (PR EoS) with van der Waals mixing rules and binary interaction parameters modeled the VLE data adequately, with much better fits for the 1-octene systems compared to the more polar nonanal systems.