An aqueous styrene- butadiene latex dispersion coating containing in-situ processed tetraethyl orthosilicate (TEOS) applied on paperboard demonstrated improved water barrier performance. Coatings containing TEOS equivalent to 0.8% silicon dioxide (SiO2; dry basis) exhibited water vapor performance of < 25 g/m(2)/day (23 degrees C, 50% relative humidity [RH]) and liquid water barrier performance Cobb 1800 s of < 6 g/m(2), when applied as a single-layer 18 g/m(2) coating. Cobb 1800 s barrier performance was still good (< 11 g/m(2)) at coat weights of 7-10 g/m(2). The use of filler materials such as kaolin improved the vapor barrier properties of the coating, but this was not critical to the liquid water barrier properties. Application: This work presents a feasible solution applicable within the conventional paper/paperboard coating process. It provides a new and effective approach and methodology to barrier coating on paper/paperboard to enhance the water vapor transmission rate (WVTR) and Cobb performance properties for use in packaging and other applications.