Non-wettable surfaces with high contact angles and facile sliding angle of water droplets have received tremendous attention in recent years. The present paper describes the room temperature (similar to 27 degrees C) synthesis of dip coated water repellent silica coatings on glass substrates using iso-butyltrimethoxysilane (iso-BTMS) as a co-precursor. Emphasis is given to the influence of the hydrophobic reagent (iso-BTMS) on the water repellent properties of the silica films. Silica sol was prepared by keeping the molar ratio of tetraethoxysilane (TEOS) precursor, methanol (MeOH) solvent, water (H2O) constant at 1:16.53:8.26 respectively, with 0.01 M NH4F throughout the experiment and the molar ratio of iso-BTMS/TEOS (M) was varied from 0 to 0.965. The effect of M on the surface structure and hydrophobicity has been researched. The static water contact angle values of the silica films increased from 65 degrees to 140 degrees and water sliding angle values decreased from 42 degrees to 16 degrees with an increase in the M value from 0 to 0.965. The water repellent silica films are thermally stable up to a temperature of 280 degrees C and above this temperature the film shows hydrophilic behavior. The water repellent silica films were characterized by the Fourier Transform Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), % of optical transmission, thermal and chemical aging tests, humidity tests, static and dynamic water contact angle measurements. (C) 2010 Elsevier B. V. All rights reserved.