The reactions of 3,3Ј-diaminobenzidine with 1,12-dodecanediol in 1 : 1-1:3 molar ratios in the presence of RuCl 2 (PPh 3 ) 3 catalyst give poly(alkylenebenzimidazole), [O(CH 2 ) 11 OOO(CH 2 ) 11 OImO/O(CH 2 ) 10 OImO] n (Im: 5,5Ј-dibenzimidazole-2,2Ј-diyl) (I a -I d ) in 71-92% yields. The relative ratio between the [(CH 2 ) 11 OOO (CH 2 ) 11 OImO] unit (A) and the [-(CH 2 ) 10 OImO] unit (B) in the polymer chain varies depending on the ratio of the substrates used. The polymer I a obtained from the 1 : 3 reaction contains these structural units in a 98 : 2 ratio. The polymers are soluble in polar solvents such as DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), and NMP (N-methyl-2-pyrrolidone) and have molecular weights M n (M w ) of 4,200 -4,800 (4,800 -6,500) by GPC (polystyrene standard). The polymerization of the diol and 3,3Ј-diaminobenzidine in higher molar ratios leads to partial cross-linking of the resulting polymers I e and I f via condensation of imidazole NH group with CH 2 OH group. Similar reactions of 3,3Ј-diaminobenzidine with ␣,-diols, HO(CH 2 ) m OH (m ϭ 4 -10), in a 1 : 3 molar ratio give the polymers containing [O(CH 2 ) mϪ1 OOO(CH 2 ) mϪ1 OImO] and [O(CH 2 ) mϪ2OImO] units with partial cross-linked structures.