A liquid composition comprising a mixture of isomers of essentially diisocyanates having the diphenylmethane structure, the distribution by weight of isomers in the composition for each 100 parts by weight of the composition being:32 to 55% of the 4,4' isomer,30 to 45% of the 2,4' isomer,5 to 12% of the 3,4' isomer,4 to 10% of the 2,2' isomer, and2 to 5% of the 2,3' isomer;and the method of making the composition by first reacting a benzyl halide with benzene, followed by nitration, hydrogenation, and phosgenation.