Following the Coleman-Noll interpretation of the second law of Thermodynamics, the Author discusses the thermodynamics of the electromagnetic field in stationary rigid materials. Recalling the concept of “quasi elastic” response for deformable bodies, introduced by Wang and Bowen, the new definition of “quasi electromagnetic” response for rigid bodies is given. The implications of the second law for this new type of constitutive relations are examined in detail. Some results of Coleman and Dill are generalized and a new characteristic condition for electrothermal and thermoelectric conduction is proposed.