A short survey of technological aspects of electrochromism with various electroactive species is given. Different approaches with inorganic and organic materials have been pursued in the past. So far widespread usage of this technology for large area applications has not been achieved. Nevertheless one major technical product, self-darkening rear-view mirrors for cars, is already well established. This article reviews some research results on electroactive polythiophenes, especially poly(3,4-alkylenedioxythiophenes). Some promising results with the commercially available electrically conducting polymer Baytron P (PEDT/PSS) are presented. It is demonstrated that an all solid-state electrochromic multilayer assembly based on a polymeric electrochromic material might be close to technical realization. The coating of large area substrates with aqueous poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) dispersion can be a way to an economically viable product.