A prototypical small area electrochromic device was fabricated. and emissivity was measured from 1 to 30 microns. The devices show change in emissivity from about 0.60 to about 0.68, that is a total modulation of 13%. The emittance performance was calculated, based on the reflectivity modulation. One difference between these devices and the more frequently explored visible light transmission devices is the utilization of crystalline tungsten oxide instead of highly disordered amorphous tungsten oxide. The crystalline tungsten oxide and nickel oxide charge storage films are characterized by IR transmission/reflection, and spectroscopic ellipsometry. A theoretical model has been developed which describes the device performance to within 10% of experimental results.