Comprehensive investigations have been made into the molecular parameters of polycationic copolymer flocculants based on acrylamide. With increase in the acrylamide fraction of the copolymers their equilibrium rigidity decreases. The effect of the composition of the copolymer on the optical anisotropy of its macromolecules has been studied. It is shown that for high concentrations of counterions in solution the electrostatic interactions in the macromolecules are completely suppressed. For a constant ionic strength in an acid medium the volume of the macromolecules rises but falls in alkaline medium which is due to change in the charge density on the polyion.