The influence of the solid state properties of manganese- and iron-based perovskites on the activity for the selective catalytic reduction of nitric oxide with propene under oxidizing conditions has been investigated. By substituting manganese for iron in the solid solution series La0.6Sr0.4Fe1-yMnyO3 +/- delta (0 less than or equal to y less than or equal to 1) and by substituting strontium for lanthanum in the solid solution series La1-xSrxMnO3+delta(0.05 less than or equal to x less than or equal to 0.50) it is shown that the catalytic activity of the perovskites depends mainly on the redox properties of the transition metal and on the number of oxygen vacancies.