A non-aqueous hydroformylation process with liquid catalyst recycle involving a hydroformylation step and one or more stages of phase separation to recover a high molecular weight aldehyde product with efficient recovery of rhodium catalyst. The process includes a hydroformylation step to prepare a non-aqueous hydroformylation reaction product composition comprising one or more aldehyde products, one or more conjugated polyolefins, a rhodium-organophosphorus ligand complex, free organophosphorus ligand, and an organic solubilizing agent for said complex and said free ligand, and thereafter one or more stages of phase separation using added water under a carbon monoxide gas, hydrogen gas, or a mixture thereof. The process requires a specific range of total pressure for the hydroformylation, a specific range of total pressure for at least one of the separation stages, and a minimum sum of the total pressure of the hydroformylation step and the total pressure of the separation stage containing said gas.