Abstract: The invention is concerned with new herbicidally active 4-phenoxy-.alpha.-phenoxy-alkanecarboxylic acid derivatives, especially propionic acid esters of the type ##STR1## bearing in the first phenoxy radical a nitro group besides another substituent R.sub.1 which is preferably a halogen atom, the CF.sub.3 group is lower alkyl, alkoxy or alkoxycarbonyl group. The invention is further concerned with herbicidal compositions containing such new derivatives and with methods for the selective control of grass-like weeds in crops of dicotyledonous and monocotyledonous cultivated plants such as cereals.