The beneficial effect (decrease of the half conversion temperature by 100 A degrees C) of potassium doping, in the range of 0-5 atoms/nm(2), on N2O decomposition over Co3O4 was analyzed by work function measurements and DFT calculations. The optimal potassium surface loading was found to be 1.8 atoms/nm(2). The effect was explained in terms of electronic promotion gauged by lowering of the catalyst work function by 0.48 eV (for K2CO3 precursor) and 0.44 eV (for KOH). The promotional effect is discussed in relation to the theoretical and experimental surface dipoles determined from Hirshfeld atomic charges and geometry of the postulated potassium adspecies and from the Topping model, respectively.