A new kind of crosslinking oligobenzotriazolylimides with terminal maleimide groups has been synthesized via an interaction of an excess of bismaleimides with 5,5'-bisbenzotriazoles in melt. Conditions of obtaining these oligomers were optimized via the syntheses of model compounds. Oligomers, according to dynamic thermogravimetric analysis (DTGA), fuse at 135160 degrees C, crosslink at 175250 degrees C, and possess the high thermal stability in air up to 410 degrees C. Using these oligomers as thermosetting binders or crosslinking agents, tough laminate plastics reinforced by a glass-fiber cloth as well as crosslinked films on base of a linear polybenzimidazole (PBI) matrix were obtained. The plastics and the crosslinked films possess high mechanical characteristics. It has been proved that the crosslinked films on base of the PBI matrix are perspective precursors to design the phosphoric acid electrolyte membranes for the medium temperature fuel cells. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011