This paper reviews a number of recently discussed electrochromic devices for modulating optical transmittance and emittance. Data are given on all-solid-state devices and on polymer-laminated devices, with and without self-powering by integrated solar cells. Special attention is devoted to flexible polyester-based devices incorporating electrochromic W oxide and Ni oxide. In particular we discuss some critical manufacturing aspects, including gas treatments for precharging of the individual electrochromic films in order to make them ready for facile device assembly as well as enhancements of the bleached-state transmittance through addition of Al or Mg to the Ni oxide.