A series of potassium-doped MgO catalysts loaded with KOH up to 15 mol% was prepared and evaluated for a single step synthesis of propionitrile from acetonitrile methylation with methanol. As the amount of potassium dope increased, both the acetonitrile conversion and the selectivity toward propionitrile increased. Based on the activity data coupled with CO2-TPD and NH3-IR ones, it was concluded that potassium doping to MgO resulted in the enhancement of both basicity and bifunctionality -methylation and hydrogenation.