AbstractPoly(methacrylic acid) containing 0.4 mol% of anthryl groups (PMA‐A) was prepared and its formation of polyelectrolyte complex (PEC) with some polycations in aqueous solution was investigated. The fluorescence intensity of the anthracene (Anth) chromophore increases with the formation of PEC, which may be caused by enhanced hydrophobicity of the microenvironment around the Anth moiety. The intensity depends strongly on the chemical structures and properties of polycations (integral or pendant type, flexibility and hydrophobicity of polymer chains, etc.) and on the experimental conditions (pH and ionic strength