Improved tensile mechanical and dynamic viscoelastic properties of silica-reinforced sulfur vulcanized rubbers can be achieved by compounding elastomers with silica in the presence of an alkoxysilane and a catalytic amount of a strong organic base. The strong organic base acts as a catalyst to accelerate the alkoxysilane-silica reaction, especially at high compounding temperatures, resulting in rubber compounds that exhibit reduced compound viscosity, improved dispersion of silica, and reduced filler flocculation after compounding, and reduced hysteresis and improved abrasion resistance in the vulcanized product, compared to similar compounds prepared at the temperature without the strong organic base catalyst.