This paper reports solid-state electrochromism observed in poly[(3,3,3-trifluoropropyl)-methylsilane-co-methylpropylsilane]. The UV absorption increases by ca. 50% at 3.1 x 10(8) V m(-1) accompanied by a 5-nm red shift of the lambda(max). The response time is less than 100 ms. The absorption recovers when the electric field is removed. This electrochromic behavior is rationalized in terms of structural changes in the silicon chain, which is the first known example of electrochromism not involving an electrochemical reaction.