A process for manufacturing an electrochromic glazing unit includes forming, on one face of a glass sheet, a complete all-solid-state electrochromic stack including in succession a first layer of a transparent conductive oxide; a layer of a cathodically colored mineral electrochromic material to form an electrochromic electrode; a layer of an ionically conductive mineral solid electrolyte; a layer of a cation intercalation material to form a counter electrode; and a second layer of a transparent conductive oxide; then heat treatment of the complete electrochromic stack by irradiation with radiation having a wavelength comprised between 500 and 2000 nm, the radiation originating from a radiating device placed facing the electrochromic stack, a relative movement being created between the radiating device and the substrate so as to raise the electrochromic stack to a temperature at least equal to 300° C. for a brief duration, for example shorter than 100 milliseconds.