This standard describes methods of zeta potential determination, both electric and acoustic, in heterogeneous systems, such as dispersions, emulsions, porous bodies with liquid dispersion medium. There is no restriction on the value of zeta potential. There is no restriction on the weight fraction of the dispersed phase; both diluted and concentrated systems are included. Particle size and pore size is assumed to be on the scale of micrometer or smaller. There is no restriction on particle shape or pore geometry. The characterization of zeta potential on flat surfaces will be discussed separately. Liquid of the dispersion medium can be either aqueous or non-aqueous. There is no restriction on liquid conductivity, dielectric permittivity, and chemical composition. The material of particles may be electrically conducting or non-conducting. Double layers may be either isolated or overlapping. There is no restriction on the double layer thickness or other properties. This standard is restricted to linear effects on electric field strength phenomena. Surface charge is assumed to be homogeneously spread along the interfaces. Effects associated with the soft surface layers containing space distributed surface charge are beyond the scope.