The present invention relates to a water-purifying composite material, especially a water-purifying composite material for use in the photocatalytic destruction of pollutants in water. The water-purifying composite materials of the invention are uniquely formed by growing crystals of photocatalytic metal compounds in situ within interlayer regions or pores within an aluminosilcate mineral structure, to thereby provide highly catalytic species for use in oxidative photocatalytic water treatments.