Abstract: A moisture absorbent material comprises a porous matrix of absorbent alumina, the volume of the pores of the matrix being between 60 and 90%, preferably 80 to 85% of the volume of the material. The average diameter of the pores is between 5.times.10.sup.-9 and 1.times.10.sup.-6 m. The pores contain a crystalline deliquescent compound, preferably calcium chloride, in an amount of between 4 and 20%, preferably between 8 and 12%, by weight, excluding any water of crystallization, with respect to the total weight of the material. The absorbent may be incorporated in a shoe insole and absorbs up to 1.5 ml moisture per gram of dry material whilst generating heat, thereby maintaining the feet of the user both warm and dry.