Abstract: A method for producing fractions of paraffin hydrocarbons of the C.sub.4 -C.sub.7 isostructure, residing in hydroisomerization of a gasoline fraction in the presence of hydrogen on a catalyst at a temperature of 320.degree.-400.degree. C., under a pressure of 20 to 60 atm., a space rate of feeding the gasoline fraction of 1.0-1.5 hour.sup.-1 ; used as a gasoline fraction being a straight run gasoline fraction boiling out within a temperature range of 85.degree.-160.degree. C. or 160.degree.-195.degree. C., or a gasoline fraction of the coking process, boiling out within a temperature range of 35.degree.-85.degree. C. or 43.degree.-170.degree. C.; the above catalyst comprising amorphous nickelalumosilicate and zeolite of the NaY type in the NiCaHY form, in a weight ratio of 60-90:40-10, respectively, the chemical composition of the catalyst being as follows (wt.%): Ni, 7-10; Al.sub.2 O.sub.3, 5-6; SiO.sub.2, 86-80; Ca, 1-2; H, 1-2.