A process for preparing polymeric, ionic compounds comprising imidazolium groups (polymeric, ionic imidazolium compounds for short) comprising reacting—an α-dicarbonyl compound,—an aldehyde,—at least one amino compound having at least two primary amino groups (referred to as oligoamine),—if appropriate an amino compound having only one primary amino group (referred to as monoamine) and a—protic acid, wherein the molar ratio of the α-dicarbonyl compound to the oligoamine is greater than 1.