Hydrogenation and hydroisomerization of kerosene fractions produced by thermal cracking of polyethylene, polypropylene and those mixtures were studied on Pt/SAPO-11 catalyst. Effects of the process parameters and the composition of the feedstocks on the isoparaffin contents, and the main performance properties of JET fuels (e.g. freezing point, smoke point) were examined. It was found that, practically sulphur- olefin- and aromatic free kerosene fractions having excellent burning properties (smoke point: 42.0 – 50. 0 mm) can be produced from the tested polyolefin cracked fractions. In the examined catalytic system JET fuel with adequate freezing point can only be produced from the clear cracked fraction of polypropylene. Due to the inadequate freezing point and density the products of the experiments cannot be used directly as engine fuel, just only as high value blending components.