Nowadays the researchers pay a great attention to the new materials, which can keep their properties during wares’ making and in further exploitation in conditions of heat influence. It’s concerned, in the first turn, the researchers, the researchers, who create and investigate the compositing materials. Ultra-high molecular weight polyethylene (UHMWPE) has high heatphysical properties. Complex of characters of this polymer gives it a constant progress and the growing demands in machine-building and other industrial branches. For the improvement of heatphysical properties it’s possible to use the fillers, which has properties of exceeding polymer matrix qualities. Chemical fibers are out looking materials in such a respect. Proceeding from it, the aim of this work was the researching of organic fiber, maintenance influence on organoplastic’s (OP) thermal heat capacity (Ср) on the basis UHMWPE. As a polymer’s matrix it was chosen a powder-like UHMWPE of Hostalen GUR 2122-mark, Ticona firm (Germany). As a reinforcing filler it was used the sharped Arselon-cotton fiber (Arselon-C) whith a maintenance of the polyoxadiazol fiber Arselon – 70 and cotton – 30 mass.%. The fiber was receipting by cutting of the combined Arselon-cotton thread (thread Arselon – 100 tex, cotton – 50 tex). Length of cutting is 2-3 mm. The composition preparing was doing by the method of dry components’ mixing in revolving electro-magnetic field [1]. Mixing time is 20-30 s. Pressing temperature of the initial UHMWPE was 513, organoplastic – 518 K. Ср OP determination was doing on the ИT-C-400 measuring instrument according to State Standard 23630.1-79. The heat-physical researches testify: increase of fiber maintenance in polymer matrix provide with lowering Ср. On the one hand, it’s caused by smaller Ср (1.25-1.41) of combined fiber Arselon-C than initial UHMWPE (2.29), on the other hand – Ср diminishing is caused by regulating of structure of binding on the border of division binding-fiber. According to growing of temperature up to 450 K Ср of researching materials is growing. It’s obvious, connected with increasing of segmental mobility of macromolecules. In region 425-475 K it is observed a strongly-pronounced jump of thermal heat capacity ΔСр, stipulated by the transition from glassy to plastic condition, it may be determined as a potential barrier of unbecoming glassy, which defines energetic difference of two conditions – glassy and plastic [2]. It’s interesting to note, magnitude ΔСр is reducing with increasing fiber’s maintenance (see table). It testifies about that for OP, containing 25% of ArselonC on the border of division of fiber-binding’s phases is occurring the greatest regulating of macromolecules of polymer and it has the greatest temperature of becoming glassy.The heat-physical characters of organoplastics in interval 173-473 КArselon-C fiber’s introducing in quantity of 5-25 mass.% is reducing to lowering of the thermal heat capacity to 11-27%.