We developed a foaming water glass (FWG), a kind of alkaline sodium silicate hydrate (lNa₂O•mSiO₂•nH₂O) and applied it to a HCl remover and a dioxin inhibitor in flue of waste incinerators. HCl emissions from PVC (polyvinyl chloride) proved to decrease substantially by incinerating the PVC with the FWG, indicating that the FWG is a useful HCl remover. HCl concentrations in flues of industrial waste incinerators were also reduced with larger efficiency than the conventional calcium hydroxide particles by injecting a diluted FWG solution as a cooling water. The reduction of HCl generation led to the decrease in dioxin concentrations in flue gas and fly ash.