2-Aminooxymethylenephenylacetic acid ester derivatives of the formula ##STR1## wherein Z.sub.1 and Z.sub.2 are hydrogen, halogen, hydroxy, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 haloalkyl, C.sub.1 -C.sub.4 haloalkoxy, C.sub.1 -C.sub.4 alkylcarbonyl, phenoxy, nitro or cyano, or Z.sub.1 and Z.sub.2, together with the linking phenyl radical, are naphthalene or hydrogenated naphthalene, and R.sub.3 is hydrogen or C.sub.1 -C.sub.12 alkyl. The compounds of this invention may be used as the free base or as a protic acid salt and are important intermediates for the manufacture of microbicides for plant protection.