In this work, a series of samples of composite materials based on ultra-high molecular weight polyethylene and a hybrid filler containing graphene nanoplates and iodized multi-walled carbon nanotubes (MWCNTs) were obtained by pressing followed by sintering. The resulting nanocomposites were studied by X-ray phase analysis and Raman spectroscopy. The iodine concentration in the modified MWCNTs was determined by energy dispersive X-ray fluorescence analysis. Assessment of the structural features of nanomaterials using X-ray phase analysis indicates the absence of iodine in the interlayer space of graphene sheets, while a change in the surface is observed. Raman spectroscopy data indicate an insignificant destructive effect of iodine on the surface of the nanomaterial. The study of electrical conductivity showed that when using iodine-modified MWCNTs as a filler, the percolation threshold shifts to lower filler concentrations, in comparison with nanocomposite samples containing unmodified nanotubes. An increase in the concentration of graphene nanoplates contributes to a twofold decrease in the percolation threshold. The maximum electrical conductivity of 5.4×10 -4 S⋅cm -1 was achieved in ultra-high molecular weight polyethylene nanocomposites containing 3 wt. % iodinated multi-walled carbon nanotubes and 1 wt. % graphene nanoplates.