Gels of a-type zirconium(IV) phosphate alkylphosphonates, ZP(C-n)(x), were prepared by reacting, at room temperature, propanol intercalated nanosized alpha-zirconium phosphate (alpha-ZrP) with propanol solutions of alkylphosphonic acids (H2Cn, n = number of carbon atoms in the alkyl chain = 4, 5, 6), with (H2Cn/Zr) molar ratios in the range 0.4-4.0. P-31 MAS NMR showed the presence of resonances due to the phosphate and phosphonate groups bonded to the Zr atoms mainly by three oxygen atoms, as in the alpha-type layer. The composition of the ZP(C-n)(x) materials, obtained by thermogravimetric analysis, ranges from x approximate to 0.2 to x approximate to 1.1. On the basis of the NMR data and of the analysis of the X-ray patterns of gels and powders, it is inferred that the ZP(C-n)(x) compounds have an alpha-type layered structure and that the reaction between alpha-ZrP and H2Cn is a topotactic anion exchange process. The evolution of the X-ray patterns during propanol deintercalation is consistent with a random distribution of the alkylphosphonate groups on the a-type layers which gives rise to porous pathways in the interlayer region. To test the possibility of using ZP(C-n)(x) as mechanical reinforcement of a polymer matrix, a starch membrane filled with 5 wt % ZP(C-6)(0.54) was prepared and characterized by stress strain mechanical tests. Besides an excellent flexibility, this membrane exhibited a proportional increase of the Young's modulus by 230% in comparison with neat starch.