Copolymers of N-isopropylacrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and 2-acetamidoacrylic acid in various ratios were synthesised by free radical solution polymerisation. Aqueous solutions of the copolymers were studied by dynamic light scattering in order to find out how the lower critical solution temperature and the conformational transition of the polymers st that temperature depend on the chemical composition of the macromolecule. The ratio of the hydrophobic and hydrophilic repeating units was observed to affect considerably the response of the polymers to an increase in temperature. The polyelectrolytes were studied also in aqueous salt solutions. The salts added into the solutions were sodium, nickel and chromium chlorides. The behaviour of the polymers was observed to depend on tile chemical nature of the added inorganic salt as well as on the ionic strength of the solutions. The added salts increase the tendency of the polymers to aggregate in solutions. The degree of aggregation, however, is not only dependent on the ionic strength; different cations clearly show a different capability of binding to the polymers.