Improved method of production of 9-(Z)-retinoic acid, in which a) a β-formyl-crotonic acid C1-C10 alkyl or phenyl ester is reacted with an isolated 9-(Z)—C15-triarylphosphonium salt by the Wittig reaction in the presence of a base to the corresponding 9-(Z)-retinoic acid ester; which b) is then saponified with a base to the corresponding 9-(Z)-retinoic acid carboxylate and then, following protonation with an acid, the desired 9-(Z)-retinoic acid is obtained, and improved method for the enrichment and isolation of the 9-(Z)—C15-triarylphosphonium salt.