A microemulsion was formulated for a model system of hydroformylation containing hydrocarbons or heptanal, water, sodium dodecylsulfate, and butanol in the presence or absence of sodium tri(m-sulfophenyl)phosphine (TPPTS-Na). The conditions were optimized by the measurements of the interfacial tension. The following order of solubilization was observed: hexane > hexene > heptanal = benzene. SDS (16-18 and 25%) was needed to solubilize nonpolar hydrocarbons and polar heptanal and benzene, respectively. An addition of TPPTS-Na caused a decrease of solubilization and shifted the curves toward higher quantities of SDS (26 and 32%, respectively). In hydroformylation of hexene carried out in optimized microemulsion a high conversion of hexene (about 97%) and the yield of heptanals (above 94%) were obtained in a very short reaction time. The ratio of isomers (n/iso) having straight and branched alkyl chains was 2.2-2.5. The products were separated by dilution of microemulsion with a butanol-water solution.