Hydroformylation process

A process comprising contacting a reaction fluid containing (a) a phosphorus acidic compound, (b) a metal-organophosphorus ligand complex catalyst that comprises a metal of Group 8, 9 or 10 complexed with an organophosphorous ligand, and, optionally, (c) free organophosphorus ligand, with an aqueous buffer solution to neutralize at least some amount of the phosphorus acidic compound of said reaction fluid to form a neutralized phosphorus acidic compound, wherein the buffer solution comprises a salt of an unsaturated aliphatic carboxylic acid represented by the formula:

• wherein R11 to R14 are hydrogen, —COOM, alkyl and cycloalkyl that contain from 1 to 24 carbon atoms and wherein at least one of R11 and R12 is a —COOM moiety and at least one of R13 and R′4 is a —COOM moiety, wherein the concentration of the salt in the buffer solution is from 0.001M to 0.8M and wherein the pH of the buffer solution is from 6 to 8.