Synthetic routes to porous ethylphosphonic acid-modified silicas with high T/Q ratios are described. The resulting materials were characterised using ²⁹Si, ³¹P and ¹³C solid state NMR, nitrogen sorption porosimetry and elemental analysis. In addition, conditions for post-modification using [VO(SO₄)·5H₂O] are described; the vanadyl derivatives were characterised by porosimetry, elemental analysis, EPR and UV-Vis spectroscopy. One of these vanadyl derivatives is a useful catalyst for the oxidation of cis-cyclooctene using aqueous hydrogen peroxide as the oxidant.