Polymethylsilsesquioxane (PMSQ) is highly heat and weather resistant and is excellent as a coating material. In the present work, the precursor for PMSQ, methyltrimethoxysilane (MTMS), was emulsified in aqueous medium with the aid of sodium silicate. It was found that at a proper concentration and ratio of MTMS to sodium silicate, the precursor MTMS could be emulsified to form an emulsion. After drying the coated emulsion on a substrate in air at room temperature, a superhydrophobic coating with water contact angle of 153° was obtained. Scanning electronic microscopy characterization indicates that the coating consists mainly of interconnected sub-100 nm particles from emulsion droplets. During drying, PMSQ formed in the emulsion droplet penetrated the outer surface of the emulsified particle, imparting hydrophobicity and nanoscale roughness to the surface. These roughness and hydrophobic properties resulted in superhydrophobicity of the coating. The process is simple and has potential for large area fabrication of superhydrophobic surfaces.