The ion exchange of hydrogenophosphate ion in Zn-Al-chloride layered double hydroxides was investigated. The chloride precursors prepared by coprecipitation at pH 10 preserved their lamellar structure following ion exchange. It was found that the aging time is important in controlling the crystallization of the phosphate-exchanged compounds; long aging times of more than 8 h lead to poorly crystallized phases. The grafting of the anion onto hydroxylated sheets by moderate thermal treatment was confirmed by a combination of several techniques, including powder X-ray diffraction (XRD), infrared (IR) spectroscopy, and thermal analyses.