The present invention refers to a process for the preparation of a mono(acyl)phosphine of the general formula (I) and/or a bis(acyl)phosphine of the general formula (II), wherein R1, R2, R3, R4 and R5 are the same or different and are independently selected from H, halogen, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl, C1-C8-alkoxy, C2-C8-alkenyloxy, C3-C8-cycloalkyl, C6-C12-aryl, C3-C8-cycloalkoxy, C7-C12-arylalkoxy, C9-C15-alkenylarylalkoxy, nitro-, C6-C12-arylsulfonyl, 4-alkylarylsulfonyl, C1-C20-alkylcarboxy, C1-C8-alkoxycarbonyl, SR14, NHR14 or NR14R15 with R14 and R15 being independently selected from H, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl and C3-C8-cycloalkyl, and an O-, S-or N-containing 5-or 6-membered heterocyclic ring; R6 is H or R6 is replaced by an alkaline earth metal cation or a mixed alkali metal/alkaline earth metal cation; Formula (II) wherein R1, R2, R3, R4, R5, R7, R8, R9, R10 and R11 are the same or different and are independently selected from H, halogen, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl, C1-C8-alkoxy, C2-C8-alkenyloxy, C3-C8-cycloalkyl, C6-C12-aryl, C3-C8-cycloalkoxy, C7-C12-arylalkoxy, C9-C15-alkenylarylalkoxy, nitro-, C6-C12-arylsulfonyl, 4-alkylarylsulfonyl, C1-C20-alkylcarboxy, C1-C8-alkoxycarbonyl, SR14, NHR14 or NR14R15 with R14 and R15 being independently selected from H, linear or branched C1-C20-alkyl, linear or branched C2-C8-alkenyl and C3-C8-cycloalkyl, and an O-, S-or N- containing 5- or 6-membered heterocyclic ring; as well as the mono(acyl)phosphine and/or bis(acyl)phosphine obtained by the process.