Abstract: The present application relates to a process for preparing a halogenated organophosphine, comprising reacting a primary or secondary organophosphine with a halogenating agent selected from (A) a compound of formula (I): (HaI)3C—C(O)—X (I) wherein X is selected from alkyl, aryl, aralkyl, alkaryl, cycloalkyl, NR1R2, C(HaI)3, OR3, -0—C(O)—R3?, or —Y—Z—Y—C(O)—C(HaI)3; R1 and R2 are each independently selected from hydrogen, alkyl, aryl, aralkyl, alkaryl, or cycloalkyl; R3 is selected from H, alkyl, aryl, aralkyl, alkaryl, cycloalkyl, or triorganosilyl; R3? is selected from C(HaI)3, alkyl, aryl, aralkyl, alkaryl, cycloalkyl; Y is independently selected from 0 or NH; Z is independently selected from alkylene, arylene, aralkylene, alkarylene, or cycloakylene; and Hal is selected from Cl or Br; or (B) a derivative of a polyol, polyamine or polyaminoalcohol comprising two or more hydroxyl and/or amino groups, in which a hydrogen atom in each of the hydroxyl and/or amino groups is replaced with a group —C(O)—C(HaI)3, w