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The method of dimerization of olefins having from 2 to 4 carbon atoms consists in that at least one said olefin is mixed, in a medium of hydrocarbon or halogenated hydrocarbon solvents at a temperature of from 0 DEG to 100 DEG C and a pressure from 1 to 40 atmospheres, with a catalyst, which is a graft copolymer of a natural or a synthetic carbon-chain rubber with vinylpyridine; said copolymer swells in said solvents and contains from 0.5 to 40 per cent of fragments of polyvinylpyridine that are complexed with a nickel salt, and contains also from 2 to 50 mole per cent of -AIRX- units, where R is an alkyl having not more than 8 carbon atoms, and X is a halogen, the aluminum atom being bound with the main chain of the copolymer through the carbon atom. The atom ratio of Al/Ni is from 1 to 20.