The invention relates to a method for producing mono-carboxyfunctionalized dialkylphosphinic acids and esters and salts thereof, characterized in that a) a phosphinic acid source (I) is reacted with olefins (IV) to yield an alkylphosphonic acid, salt or ester (II) thereof in the presence of a catalyst A, b) the alkylphosphonic acid thus obtained, salt or ester (II) thereof is reacted with an α,β-unsaturated carboxylic acid derivative (V) to yield a mono-carboxyfunctionalized dialkylphosphinic acid derivative (III) in the presence of a catalyst B, wherein R1, R2, R3, R4, R5, R6, R7 are the same or different and stand independently of each other, among other things, for H, C1-C18 alkyl, C6-C18 aryl, C6-C18 aralkyl, C6-C18 alkylaryl, and X and Y are the same or different and stand independently of each other for H, C1-C18 alkyl, C6-C18 aryl, C6-C18 aralkyl, C6-C18 alkylaryl, Mg, Ca, Al, Sb, Sn, Ge, Ti, Fe, Zr, Zn, Ce, Bi, Sr, Mn, Cu, Ni, Li, Na, K and/or a protonized nitrogen base, and the catalyst A is formed by transition metals and/or transition metal compounds and/or catalyst systems composed of a transition metal and/or a transition metal compound and at least one ligand, and catalyst B is formed by compounds forming peroxides and/or peroxo compounds and/or azo compounds and/or alkali metals and/or alkaline earth metals, alkali hydrides, alkaline earth hydrides and/or alkali alcoholates and alkaline earth alcoholates.