Hydrophobic antireflective coatings with a low refractive index were prepared via a base/acidcatalyzed twostep sol–gel process using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors, respectively. The basecatalyzed hydrolysis of TEOS leads to the formation of a sol with spherical silica particles in the first step.