Based on earlier experiences with alpha- and gamma-zirconium phosphate, zirconium phosphate-phosphite (ZrPP) containing silica (ZrSiPP) has been prepared, and its structure identified by XRD. The thermal behaviour and specific surface area have also been determined. On the basis of experimental data for SiZrPP, the following monoclinic cell parameters of : a = 0.7622 nm, b = 0.5956 nm, c = 2.2105 nm and beta = 111.4 degrees (different from those of ZrPP) were calculated. SiZrPP has five times higher specific surface area (52.6 m(2) . g(-1)) than ZrPP and it shows characteristic thermal decomposition.