The effect of potassium doping on electronic surface properties of molybdenum carbide (Mo2C) was investigated by species-resolved thermal alkali desorption techniques, work-function measurements, and density-functional theory calculations. The activation energies for desorption of K and K+ were determined and used for work-function assessment via the Schottky cycle. The results were compared with the parallel contact potential difference measurements, and a variation of the Fermi level upon doping was rationalized in terms of the potassium coverage and surface dipole moment. The tight correlation between the work-function changes and the rate constant of indole hydrodenitrogenation was observed and discussed in terms of electrophobic promotion.