A reversible electrochromic effect has been observed for the first time in flame spray pyrolysis (FSP) processed epsilon-WO3 thin films without the use of an ion storage layer and an electrolytic layer. The dark coloration that appears upon the application of a voltage in films deposited on top of interdigitated gold electrodes is localized to the low voltage (-) electrode arm and it switches to the opposite arm upon a reversal of the polarity. Raman spectroscopy indicated that the coloration was not due to intercalation. It is argued here that the coloration is driven by the asymmetric ferroelectric properties of the epsilon-WO3 crystals and that this electrochromic reversibility is intrinsically coupled with the polarization switching of the device.