Complex formation of cerium (III) with 2-[2-hydroxyphenilazo] naphthalene-1,8-dyhydroxy-3,6-disulphonate sodium (H3R) in the presence and the absence of bromide cetyltrimethylammonia has been studied. A parity of components is equal to 1:2 in homogeneous and to 1:2:2 in different ligand compounds. The influence of foreign ions to complex formation has been examined.