Stabilization of fluorophosphite-containing catalysts

Disclosed are novel catalyst systems comprising (1) a diorgano fluorophosphite ligand; (2) rhodium, wherein the ratio of gram moles fluorophosphite ligand (1) to gram atoms of rhodium is at least 1:1; and (3) a Group VIII metal, other than rhodium, or Group VIII metal-containing compound, in an amount effective to reduce the formation of HF during the use of the catalyst system. The presence of the other Group VIII metal decreases the amount of hydrogen fluoride produced during the use of the catalyst system. The hydrogen fluoride originates from very low level degradation of the ligand. Also disclosed are novel catalyst solutions of the aforesaid catalyst system and the use of the catalyst system in the hydroformylation of olefins to produce aldehydes.