The electromagnetic polarizabilities and charge radius of pions in a chiral model based on the concept of the instanton vacuum are calculated. The effective action for pions is derived in the quasi-classical approximation. The differential probability for the production of pairs of pions by an external constant electromagnetic field is found on the basis of exact solutions of the equation for pions. The expressions obtained generalize the Schwinger formulae for electron - positron production taking into account the complex structure of pions. At a critical value of the electric field the number of pions produced is increased by about 20% compared with point-like pions. We also found the imaginary part of the effective Lagrangian for the electromagnetic field in the presence of pions.