The stability effect of Mn dopand on the potassium loss from beta-ferrite, the active phase of a styrene catalyst, has been quantified for the first time in succinct measurements by means of a species-resolved (K and K+) thermal alkali desorption technique. Upon introduction of 2 wt% of Mn the desorption energies increased by 1.06 eV for ions, whereas the atomic barrier, which is crucial for the potassium volatilization, was enhanced by 1.52 eV. As a result, both K desorption fluxes are significantly extinguished. (C) 2003 Elsevier Inc. All rights reserved.