Abstract: The process is for the manufacture of phenoxylactic acids and their derivatives of the general formula: ##STR1## (in which R.sub.1 and R.sub.2, identical or different, can represent hydrogen atoms, methyl residues, methoxy groups or halogens; Y represents an OH or O--CO--R.sub.3 group with R.sub.3 representing either an aliphatic residue possibly substituted by a halogen, or an aromatic residue possibly substituted on the nucleus by one or several methyl, methoxy, halogen groups or lastly a heterocyclic group; Z represents OH group or an ##STR2## with R.sub.4 representing an alkyl or aryl radical and R.sub.5 hydrogen or an alkyl radical, NR.sub.4 R.sub.5 possibly also representing the morpholinyl radical). A cyanhydrin is subjected to a Ritter reaction (reaction with tert. butanol or isobutene in the presence of an acid).