The authors present an application of chitosan membranes for the removal of heavy metal ions. Investigations covered membranes produced by phase inversion. Additionally, separation properties of acetylated membranes were tested. Low-viscous chitosan produced by the Sea Fisheries Institute-Poland was used in the experiments. The investigations were carried out for the transition metal ions Cr(VI), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II). A method for metal ions separation by means of chitosan membranes was proposed. The metal ions were complexed in the membrane during ultrafiltration of the solution. The separation ability of the membranes was investigated for individual metal ions and for a mixture. The effect of the pH of the solution on separation properties of membranes was determined. The concentration of metal ions was investigated by the method of inductively coupled plasma (ICP) atomic emission spectrometry. The investigations show the suitability of chitosan membranes produced by the phase inversion method for the removal of metal ions.