The present invention generally relates to polysilicate microgels. More specifically, the invention relates to a process for preparing aqueous polysilicate microgels which comprises mixing an aqueous solution of alkali metal silicate with an aqueous phase of silica-based material having a pH of 11 or less and an additional compound which is a metal salt other than an aluminium salt, to polysilicate microgel per se and to the use thereof as flocculating agents in paper making and water purification. The invention further relates to a process for the production of paper from a suspension of cellulosic fibres, and optional filler, which comprises adding to the suspension at least one cationic or amphoteric organic polymer and a polysilicate microgel, forming and draining the suspension on a wire.