Abstract: A process for retanning leather has been found, which is characterized in that a) a tanned leather is treated in aqueous liquor in the presence of hollow microspheres filled with blowing agent, b) the leather obtained according to a) is dried after further optional retanning steps and c1) treated with steam at 80 to 120° C., in particular at 80 to 100° C., or c2) with infrared radiation having a wavelength of 0.7 to 100 ?m, it also being possible for a finishing step b1) and/or a milling step b2) to follow at a time after the drying step b).