Abstract: In producing silica glass, which may contain additional metal(s) such as Ti or Zr, from a solution of a silicon alkoxide, mixed with alkoxide(s) of the additional metal(s) where necessary, in water and a hydrophilic organic solvent by shaping the solution into a desired form such as a coating film on a substrate, self-supporting film, fiber or lump when the solution exhibits a suitably high viscosity and sufficiently heating the shaped solution, a water-soluble organic polymeric substance is added to the solution as a viscosity adjusting agent to soon increase the viscosity of the solution to the desirable level. Therefore, shaping of the solution can be performed without awaiting the progress of hydrolysis of the alkoxide in the solution, and the glass can be obtained with improved uniformity of its properties. A cellulose ether is preferred as the viscosity adjusting agent, and hydroxypropyl cellulose is particularly preferable.