Novel substituted phenoxyalkanecarboxylic acid esters of the formula ##STR1## in which R.sup.1 and R.sup.2, independently of one another, are a hydrogen atom, a halogen atom, a lower alkyl group or a nitro group, orR.sup.1 and R.sup.2, together with the benzene ring to which they are bonded, are a naphthalene ring,R.sup.3 and R.sup.4, independently of one another, are a hydrogen atom or a methyl group,n is 1 or 2,m is 0 or 1,X is an oxygen atom, a sulfur atom, a sulfonyl group or a group of the formula ##STR2## in which R.sup.6 is a lower alkyl group, R.sup.5 is a hydrogen atom or a halogen atom, andY is an oxygen atom or a sulfur atom, and the use of the new compounds as herbicides.