The oligomerization of 1-octene in the presence of micro- and micro-mesoporous catalysts based on zeolite Y (SiO2/Al2O3 = 4.9) has been studied. The results of low-temperature nitrogen adsorption confirm the formation of mesopores with a diameter of 2-4 nm in the micro-mesoporous catalysts. An ammonia temperature-programmed desorption study of the acid properties of the synthesized zeolite catalysts has shown that the preparation of micro-mesoporous samples is accompanied by a decrease in the concentration and strength of acid sites. A comparison of the catalytic properties of the microporous and micro-mesoporous zeolites has revealed that the latter are the most active in 1-octene oligomerization and allow octene oligomers to be obtained with a selectivity of 65% at the 100% conversion of the monomer. The use of zeolite catalysts with the micro-mesoporous structure in the oligomerization of 1-octene affords oligomers with a broader molecular-mass distribution (degree of oligomerization n = 2-5) than on the microporous samples (n = 2 to 3).