The invention relates to a process for preparing mono-allyl-functionalized dialkylphosphinic acids, esters and salts with allylic compounds, characterized in that a) a phosphinic acid source (I) is reacted with olefins (IV) in the presence of a catalyst A to give an alkylphosphonous acid, or salt or ester thereof (II), b) the alkylphosphonous acid, or salt or ester thereof (II) thus formed is reacted with allylic compounds of the formula (V) in the presence of a catalyst B and of a base to give a mono-allyl-functionalized dialkylphosphinic acid derivative (III), where R1, R2, R3, R4, R5, R6, R7, R8, R9 are the same or different and are each independently, inter alia, H, C1-C18-alkyl, C6-C18-aryl, C6-C18-aralkyl, C6-C18-alkylaryl, and X is 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 protonated nitrogen base, and the catalysts A and B are transition metals and/or transition metal compounds and/or catalyst systems which are composed of a transition metal and/or a transition metal compound and at least one ligand.