Solutions in closed form are presented for the polarization behavior and the distribution of current and potential in idealized, one-dimensional porous electrodes in the case of a simple oxidation-reduction reaction under pure activation control. Exact solutions are derived for transfer coefficients of 1/3, 1/2, and 2/3 for electrodes of finite length, while solutions for semi-infinite electrodes are given for transfer coefficients of 1/4, 1/3, 1/2, 2/3, and 3/4. An approximate method for calculating current and potential distributions in porous electrodes is proposed which is valid for any value of the transfer coefficient, and exact and approximate solutions are compared.