Abstract: Phenoxyphenoxy-propionic acid derivatives of the formula ##STR1## exhibit an outstanding herbicidal activity against a wide variety of weed grasses and are well tolerated by dicotyledonous crop plants and various cereals.

Abstract: Compounds of the formula I ##SPC1##in which R represents hydrogen, halogen, alkyl having 1 to 4 carbon atoms, alkoxy and alkylthio having 1 to 4 carbon atoms, cyclohexyl, cyclopentyl, and phenyl, R.sup.1 represents hydrogen, halogen, alkyl having 1 to 4 carbon atoms, and alkenyl having 2 to 4 carbon atoms, X and Y each are oxygen or sulfur, R.sup.2 represents hydrogen, alkyl having 1 to 10 carbon atoms, alkoxyalkyl having 2 to 6 carbon atoms, alkyl-amino having 2 to 4 carbon atoms, or phenyl, R.sup.3 represents hydrogen or alkyl having 1 to 4 carbon atoms, R.sup.4 represents hydroxyl, --O-alkyl having 1 to 10 carbon atoms, --S-alkyl having 1 to 6 carbon atoms, --O-- alkenyl having 2 to 4 carbon atoms, --O-cyclohexyl, --O-cyclopentyl, a phenoxy or phenylthio radical optionally substituted once or twice with halogen; --NH.sub.2, --NH-alkyl having 1 to 4 carbon atoms, --N,N-dialkyl or ##EQU1## HAVING 1 TO 4 CARBON ATOMS IN EACH ALKYL GROUP, A --NH-phenyl radical substituted with halogen, --CF.sub.3, --OCF.sub.