FIELD: industrial organic synthesis. SUBSTANCE: aromatic polyisocyanates are prepared by interaction of aromatic amine containing two primary amino functions and C6-C10- aromatic moiety or mixture of isomers thereof with phosgene in mixed-type reactor. Reactor has first mixing zone, constituting 20 to 80% of the total volume of reactor and having length of the same order as its cross-section width, and second zone, wherein reaction mixture moves according to principle resembling that of piston and which constitutes 80 to 20% of the total volume of reactor and has is length larger than its cross-section width. The two reactants enter reactor in gas form with phosgene in 5 to 60% molar excess to amino functions of aromatic amine. EFFECT: reduced excess if phosgene and increased yield of desired products. 11 cl, 2 ex
