Mesoporous silica particles were prepared by sol-gel method in one-step synthesis, in acidic condition, from tetraethoxysilane (TEOS) and methyl­triethoxysilane (MTES), varying the molar ratio of the silica precursors. Nitric acid was used as catalyst at room temperature and hexadecyltrimethyl ammoni­um bromide (CTAB) as structure directing agent. Optical properties, porosity and microstructure of the materials in function of the MTES/TEOS ratio, were evaluated using infrared spectroscopy, nitrogen adsorption, and small angle X-ray scattering. All materials show ordered pore structure and high specific surfaces, making them suitable as drug delivery systems. Drug loading and release tests using ketoprofen were performed to assess their performance for drug delivery applications. The amount of the methylated precursor used in the synthesis had little effect on the drug loading capacity, but had a strong influence on the initial rate of the drug release.