Herein disclosed is a method of producing synthesis gas from carbonaceous material, the method comprising: (a) providing a mixture comprising carbonaceous material and a liquid medium; (b) subjecting the mixture to high shear under gasification conditions whereby a high shear-treated stream comprising synthesis gas is produced; and (c) separating a product comprising synthesis gas from the high shear-treated stream. Herein also disclosed is a method for producing a liquid product. The method comprises forming a dispersion comprising gas bubbles dispersed in a liquid phase in a high shear device, wherein the average gas bubble diameter is less than about 1.5 μm; contacting the dispersion with a multifunctional catalyst to form the liquid product; and recovering the liquid product. In an embodiment, the liquid product is selected from the group consisting of C2+ hydrocarbons, C2+ oxygenates, and combinations thereof.