"Non-firing" ceramics have recently attracted much attention because many functional ceramics can be achieved by this method without the sintering process. The underlying idea of this method is to activate the surface of the particles by ball milling. In this study, the effect of adsorbed water on the surface of raw silica powder was investigated. Amorphous silica powder was mechanically treated by a rotating ball mill system and the surface activity of the raw and treated silica powders was measured based on the water adsorbed volume on the powder surface. The results showed that the surface activity of the silica powder increased with the increasing adsorbed water volume on the surface of the silica powder. In addition, better mechanical properties evaluated by the Vickers hardness test were achieved for the silica with more water adsorbed on its surface. The effect of milling energy and ball to powder ratio on activation of the silica was also investigated. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.