NOVELTY - The stretchable electrochromic device comprises a stretchable conductive substrate, an electrochromic material disposed on or impregnating the stretchable conductive Substrate to form a stretchable electrochromic substrate, a stretchable transparent polymeric electrolyte coating or impregnating the stretchable conductive substrate and/or electrochromic substrate, electrodes, and a potential source. The stretchable transparent polymeric electrolyte comprises thermoplastic polyurethane, thermoplastic polyurea, polyethylene oxide and/or cross-linked polyethylene oxide.    USE - The stretchable electrochromic device such as a photovoltaic or a battery is useful in an article including a garment (all claimed) such as wearable electronic garments, where the stretchable electrochromic device is absorptive/transmissive or absorptive/reflective stretchable electrochromic device.    ADVANTAGE - The stretchable electrochromic device exhibits improved flexibility and stretchability, rapid switching property, and high contrast thus providing comfortable and easily cleanable garments.    DETAILED DESCRIPTION - The stretchable electrochromic device comprises a stretchable conductive substrate, an electrochromic material disposed on or impregnating the stretchable conductive substrate to form a stretchable electrochromic substrate, a stretchable transparent polymeric electrolyte coating or impregnating the stretchable conductive substrate and/or electrochromic substrate, electrodes, and a potential source. The stretchable transparent polymeric electrolyte comprises thermoplastic polyurethane, thermoplastic polyurea, polyethylene oxide and/or cross-linked polyethylene oxide and salt such as an ionic liquid. The thermoplastic polyurethane is prepared from a thermoplastic polyurethane prepolymer, and the thermoplastic polyurea is prepared from a thermoplastic polyurea prepolymer. The stretchable electrochromic substrate is a stretchable conductive fabric or stretchable conductive fiber comprising an electrochromic material such as a conjugated polymer. The electrochromic material is disposed on the stretchable conductive fiber or disposed on or impregnates the stretchable conductive fabric. The potential source is present in electrical connection with the electrodes. The stretchable polymeric electrolyte is disposed between the electrodes. One of the electrodes comprises stretchable electrochromic fibers or fabrics. An INDEPENDENT CLAIM is included for a method of forming a stretchable electrochromic device.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross-sectional view of an electrochromic device.    Second non-electrically conductive fiber (110)    First non-electrically conductive fiber (120)    First electrochromic, conductive layer (130)    Second electrolyte layer (140)    First electrolyte layer. (150)