Layered alpha-titanium(IV) phenylphosphonate can be prepared with a broad variation in surface area and porosity. Several sources for tetravalent titanium ion and different synthetic procedures have been studied. The solids were characterized by powder X-ray diffraction (XRD), thermogravimetric (TG) analysis, IR and P-31 magic angle spinning (MAS) NMR spectroscopies, N-2 adsorption-desorption isotherms, and scanning electron microscopy (SEM). The materials obtained have a high thermal stability as shown by TG analysis, N-2 adsorption-desorption isotherms of the solids correspond to type IV of the BDDT classification and show hysteresis loops of type H-3, characteristic of solids with slit-shaped pores. The materials are essentially mesoporous, and any mensurable microporosity was not detected. BET surface areas, porosity, and crystallinity are markedly dependent on the preparation procedure.