A photochromic structure includes a plastic support of optical grade with good light transparency, having at least one face with an adhesive layer impregnated with a solution of a solvent with photochromes, having a flexible host matrix for the photochromes, which is mounted by adhesion onto another support. A structure with a uniform flexible photochromic matrix, which has rapid transition times, notably a rapid relaxation time, is thus obtained. The structure is mountable, and advantageously repositionable. It is produced via a process using roll-milling combined with a system for dispensing the solvated solution of photochromes upstream of the rolls, via which a support strip of an adhesive is entrained by the rolls, and the adhesive is gradually impregnated and then laminated on another support.