The invention relates to a method for obtaining a modified collagen absorbent product from leather, which comprises aerating flat pieces of leather during a time period of between 15 and 45 days; collecting the pieces with an initial relative humidity value of 45% or less; grading the pieces by size; obtaining pieces with a maximum final length of between 0.5 and 1.5 mm; placing the pieces in a drying oven; applying heat in the drying oven so that the pieces are exposed to a temperature of 285°C or less during a time period; controlling the temperature applied during the time period so that the relative humidity is reduced to a final value of between 0.5% and 5% in the pieces; reducing the temperature of the pieces to an ambient temperature; and obtaining the modified collagen absorbent product from leather.