Biphasic hydroformylation using water-soluble rhodium catalysts is advantageous with regard to catalyst recovery and product separation. Higher olefins cannot be converted due to their immiscibility with water. The 1-dodecene as model alkene was successfully hydroformylated in microemulsions with reaction rates higher than in a two-phase system. Technical grade polyglycolether type surfactants were used for the preparation of the microemulsions. Suitable microemulsions were found for carrying out hydroformylation reactions at different temperatures. Catalyst recovery can be achieved by phase separation followed by ultrafiltration.