The present invention relates to a composition of aqueous gel type comprising from 7.5% to 13.5% by dry weight, relative to its total weight, of at least one modified crosslinked C1-C4 carboxyalkyl starch and at least one C2-C5 monoalcohol. A composition according to the invention is in particular of use as a skin cleansing mask, in particular a face cleansing mask. The invention also relates to a process for the preparation thereof, to a process for cosmetic treatment of keratin materials and to a cosmetic process for cleansing a keratin material.