The invention relates to a method for producing organophosphites, organophosphonites and organophosphinites by the condensation of phosphorus trihalides or organophosphorus halides with organic compounds that carry hydroxy groups, in the presence of polymeric alkaline ion-exchange resins. The inventive method permits the production of trivalent organophosphorus compounds, which can be used e.g. as ligands in rhodium complexes that can be utilised as a catalyst in hydroformylation.