The kinetics of the layer formation process and the corrosion process have been determined from the relation between the stationary ( i c ,0) and non-stationary ( i c ) corrosion rates and the rate of layer formation ( i ι) at passive iron in acid solutions. The rates of both processes depend on the potential difference ε 2,3 at the passive-oxide/electrolyte-solution interface. The fact that i c and i c,0 are independent of the electrode potential is explained by a nearly constant composition of the passive oxide in contact with the solution (Fermi level within the band gap). Linear relations, such as log i ι + = a + (α ι +/α c +)·log i c , are obtained, which are explained by charge-transfer hindrance. The apparent charge-transfer coefficients are α ι + = 1·43 and α ι − = 0·57 for the layer formation and removal reaction, and α c + = 0·84 for the corrosion reaction. From the pH dependence (pH = 0.35–2·90) of i ι and i c,0 the reaction orders of the hydrogen ions are found to be approximately μn ι + = −1 and ν c = 0. The corrosion cd depends on the sulphate concentration, with a reaction order ν s = ß = 0·16. From this, the kinetics of the oxide formation H 2O·aq ⇆ OH − · ox + H +·aq (preceding equilibrium), OH −·ox↔O 2−·ox + H +·aq (rate-determining) and the kinetics of the corrosion process Fe 3+·ox + SO 4 2−·aq ⇆ FeSO 4 +·ad (adsorption equilibrium, Temkin conditions), FeSO 4 +·ad → FeSO 4 +·aq (rate-determining), with following dissociation of the complex can be deduced. The apparent charge-transfer coefficients are interpreted by α ι + = 1 + α ι, α ι − = 1 − α ι and α c + = α + 2ßγ s (ga ι, α, true charge-transfer coefficients).