Abstract: A dispersion of exfoliated particles which includes at least one nitrogen-containing basic compound (A) which is a tertiary amine or a quaternary ammonium hydroxide having at least one alkyl group having 3 or 4 carbon atoms, and in which exfoliated particles (C) produced by interlayer-exfoliating a proton-type layered polysilicate compound (B) are dispersed in an aqueous solution (D) having 10 vol % to 90 vol % of an alcohol having 1 to 3 carbon atoms; and a film-forming composition, a porous body-forming composition, an LB film, a coating film, a free-standing membrane, a proton conductor, an electrolyte membrane for fuel cells, and a porous body each containing exfoliated particles.