Experience in operating a sulfuric-acid alkylation jet reactor of new design - with no mixers and heat-exchange bank and a process scheme that includes this reactor, a hydrocyclone, three-phase separator, and circulating centrifugal pumps are described. An additional quantity of feedstock is added to the jet reactor operating in tandem with a cascade reactor without addition of circulating isobutane. The concentration of high-octane components in the products of the reaction, i.e., the alkylate production volume, increases. The resulls of operating the jet reactor in incorporation of propylene feedstock front the cascade reactor to "butylene" alkylate are reported. The additional volume of "propylene" alkylate is up to 1/3 of the total output of the unit. distillation is improved, and the Motor Octane Number decreases insignificantly - by a maxinium of 0.5 points.