Dimethyl carbonate (DMC) can be applied as a greener alternative to more hazardous materials, e.g. phosgene or dimethyl sulfate. Herein, one-pot synthesis of DMC from propylene oxide, methanol and CO₂ using alkali halide catalysts under mild conditions was studied. Addition of Zn powder to the K₂CO₃-NaBr-ZnO catalyst system was seen to increase DMC selectivity from 19.8% (TOF = 39.0 h⁻¹) to 40.2% (TOF = 78.1 h⁻¹) at 20 bar and 160 °C for 5 h. Catalyst characterisation showed that Zn powder increases the stability of the catalyst, preventing the active ingredients on the catalyst surface from leaching. An increase in propylene oxide conversion to DMC is attributed to the increase of Zn²⁺ ions in the reaction solution. Elevated pressure was not found to be a necessary reaction condition for transesterification. This study shows that increased selectivity to DMC can be achieved at mild conditions with the addition of Zn powder.