We have utilized wet-chemical etching of ellipsoidal silica nanoparticles (ESNs) to form silica nanoshells of a range of elliptical morphologies, with the thicknesses of the ellipsoidal silica nanoshells (ESSs) controlled through variation of synthesis conditions. A mechanism has been proposed to explain how the nanoshells are formed, and we demonstrate that the porosity of the silica ellipsoid plays a role in generating silica shells. Our self-templated, wet-etching approach is an attractive alternate procedure to the approaches presently in existence for the following reasons: (i) it is a facile, one-step process that directly produces ellipsoidal silica nanoshells, while overcoming barriers (such as requirement of removing a solid-core template seed) utilized in many reported chemical etching studies; (ii) it results in ellipsoidal silica nanostructures with dimension less than 100 nm; (iii) with an appropriate etchant, the roughness of the silica shells can be well-controlled; and (iv) it results in tunable, uniform size particles with controllable shell thicknesses. Moreover, the silica materials with the unique structures might be adjusted to meet practical application requirements. (C) 2012 Elsevier Inc. All rights reserved.