The invention relates to the process for preparing ethylenedialkylphosphinic acids, esters and salts, wherein a) a phosphonic acid source (I) is reacted with olefins (IV) in the presence of a catalyst A to give an alkylphosphonous acid (II), or salt or ester thereof, b) the alkylphosphonous acid (II), or the salt or ester thereof, is reacted with an acetylenic compound (V) in the presence of a catalyst B to give the ethylenedialkylphosphinic acid derivative (III) where R1, R2, R3, R4, R5, R6, R11, R12, R13, R14 are the same or different and are each independently H, C1-C18-alkyl, C6-C18-aryl, C6-C18-aralkyl, C6-C18-alkylaryl, where the C6-C18-aryl, C6-C18-aralkyl, C6-C18-alkylaryl groups may be substituted by —C(O)CH3, OH, CH2OH, NH2, NO2, OCH3, SH and/or OC(O)CH3, and X is Mg, Ca, Al, Sb, Sn, Ge, Ti, Fe, Zr, Zn, Ce, Bi, Sr, Mn, Cu, Ni, Li, Na, K, H and/or a protonated nitrogen base, and/or is H, C1-C18-alkyl, C6-C18-aryl, C6-C18-aralkyl, C6-C18-alkylaryl, (CH2)kOH, CH2—CHOH—CH2OH, (CH2)kO(CH2)lH, (CH2)k—CH(OH)—(CH2)lH, (CH2—CH2O)kH, (CH2—C[CH3]HO)kH, (CH2—C[CH3]HO)k(CH2—CH2O)lH, (CH2—CH2O)k(CH2—C[CH3]HO)H, (CH2—CH2O)k-alkyl, (CH2—C[CH3]HO)k-alkyl, (CH2—C[CH3]HO)k(CH2—CH2O)l-alkyl, (CH2—CH2O)k(CH2—C[CH3]HO)O-alkyl, (CH2)kNH2, (CH2)kN[(CH2)lH]2, where k and l are the same or different and are each independently an integer from 0 to 20, and m is 1 to 4, and the catalyst A comprises 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 the catalyst B comprises electromagnetic radiation.