Mixed alcohol synthesis (MAS) from syngas involves an overall reduction in the number of moles (i.e., volume reduction) and is highly exothermic. As such, the high-pressure, dense-phase solvent conditions of a supercritical reaction medium afford opportunities to enhance the performance of these reactions. In this paper, the effect of supercritical hexanes (a mixture of hexane isomers) on the reaction performance of MAS was studied in a fixed bed reactor. Experiments were carried out over a 0.5 wt % K promoted Cu based mixed metal oxide catalyst in the temperature range of 200 degrees C-300 degrees C, a partial pressure of syngas of 4.5 MPa, and the hexanes/syngas molar ratio ranging from 0 to 3. The results of mixed alcohol synthesis under supercritical hexanes phase conditions demonstrated remarkable enhancement in CO conversion and methanol productivity, while the CH, and CO2 selectivity was notably reduced. In addition, the effect of temperature has also been investigated on conversion, selectivity, and alcohol productivities for operation under both gas phase and supercritical phase conditions.