We present the details of the sol-gel processing used to realize inverse silica opal, where the silica was activated with 0.3 mol% of Er3 ions. The template (direct opal) was obtained assembling polystyrene spheres of the dimensions of 260 nm by means of a vertical deposition technique. The Er3 -activated silica inverse opal was obtained infiltrating, into the void of the template, the silica sol doped with Er3 ions and subsequently removing the polystyrene spheres by means of calcinations.Scanning electron microscope showed that the inverse opals possess a fcc structure with a air hollows of about 210 nm and a photonic band gap, in the visible range, was observed from reflectance measurements. Spectroscopic properties of Er3 -activated silica inverse opal were investigated by luminescence spectroscopy, where, upon excitation at 514.5 nm, an emission of 4I13/2 → 4I15/2 of Er3 ions transition with a 21 nm bandwidth was observed. Moreover the 4I13/2 level decay curve presents a single-exponential profile, with a measured lifetime of 18 ms, corresponding a high quantum efficiency of the system.